This documentation is automatically generated by online-judge-tools/verification-helper
#define PROBLEM "https://judge.yosupo.jp/problem/chromatic_number"
#include "../default/t.cpp"
#include "modint/dynamicMontgomeryModInt.cpp"
#include "numtheory/fastFactorize.cpp"
#include "combi/chromaticNumber.cpp"
signed main() {
ios::sync_with_stdio(false), cin.tie(NULL);
int n, m; cin >> n >> m;
vector g(n, vector<bool>(n, false));
for(int i = 0; i < m; i++) {
int u, v; cin >> u >> v;
g[u][v] = g[v][u] = true;
}
cout << chromatic_number(g) << '\n';
return 0;
}
#line 1 "test/chromatic_number.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/chromatic_number"
#line 1 "default/t.cpp"
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfenv>
#include <cfloat>
#include <chrono>
#include <cinttypes>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <streambuf>
#include <string>
#include <tuple>
#include <type_traits>
#include <variant>
#include <bit>
#include <compare>
#include <concepts>
#include <numbers>
#include <ranges>
#include <span>
#define INT128_MAX (__int128)(((unsigned __int128) 1 << ((sizeof(__int128) * __CHAR_BIT__) - 1)) - 1)
#define INT128_MIN (-INT128_MAX - 1)
#define clock chrono::steady_clock::now().time_since_epoch().count()
using namespace std;
template<class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2> pr) {
return os << pr.first << ' ' << pr.second;
}
template<class T, size_t N>
ostream& operator<<(ostream& os, const array<T, N> &arr) {
for(size_t i = 0; T x : arr) {
os << x;
if (++i != N) os << ' ';
}
return os;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T> &vec) {
for(size_t i = 0; T x : vec) {
os << x;
if (++i != size(vec)) os << ' ';
}
return os;
}
template<class T>
ostream& operator<<(ostream& os, const set<T> &s) {
for(size_t i = 0; T x : s) {
os << x;
if (++i != size(s)) os << ' ';
}
return os;
}
template<class T1, class T2>
ostream& operator<<(ostream& os, const map<T1, T2> &m) {
for(size_t i = 0; pair<T1, T2> x : m) {
os << x;
if (++i != size(m)) os << ' ';
}
return os;
}
#ifdef DEBUG
#define dbg(...) cerr << '(', _do(#__VA_ARGS__), cerr << ") = ", _do2(__VA_ARGS__)
template<typename T> void _do(T &&x) { cerr << x; }
template<typename T, typename ...S> void _do(T &&x, S&&...y) { cerr << x << ", "; _do(y...); }
template<typename T> void _do2(T &&x) { cerr << x << endl; }
template<typename T, typename ...S> void _do2(T &&x, S&&...y) { cerr << x << ", "; _do2(y...); }
#else
#define dbg(...)
#endif
using ll = long long;
using ull = unsigned long long;
using ldb = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<typename T> using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T> using max_heap = priority_queue<T>;
template<ranges::forward_range rng, class T = ranges::range_value_t<rng>, class OP = plus<T>>
void pSum(rng &v) {
if (!v.empty())
for(T p = v[0]; T &x : v | views::drop(1))
x = p = OP()(p, x);
}
template<ranges::forward_range rng, class T = ranges::range_value_t<rng>, class OP>
void pSum(rng &v, OP op) {
if (!v.empty())
for(T p = v[0]; T &x : v | views::drop(1))
x = p = op(p, x);
}
template<ranges::forward_range rng>
void Unique(rng &v) {
ranges::sort(v);
v.resize(unique(v.begin(), v.end()) - v.begin());
}
template<ranges::random_access_range rng>
rng invPerm(rng p) {
rng ret = p;
for(int i = 0; i < ssize(p); i++)
ret[p[i]] = i;
return ret;
}
template<ranges::random_access_range rng, ranges::random_access_range rng2>
rng Permute(rng v, rng2 p) {
rng ret = v;
for(int i = 0; i < ssize(p); i++)
ret[p[i]] = v[i];
return ret;
}
template<bool directed>
vector<vector<int>> readGraph(int n, int m, int base) {
vector<vector<int>> g(n);
for(int i = 0; i < m; i++) {
int u, v; cin >> u >> v;
u -= base, v -= base;
g[u].emplace_back(v);
if constexpr (!directed)
g[v].emplace_back(u);
}
return g;
}
template<class T>
void setBit(T &msk, int bit, bool x) {
msk = (msk & ~(T(1) << bit)) | (T(x) << bit);
}
template<class T> void flipBit(T &msk, int bit) { msk ^= T(1) << bit; }
template<class T> bool getBit(T msk, int bit) { return msk >> bit & T(1); }
template<class T>
T floorDiv(T a, T b) {
if (b < 0) a *= -1, b *= -1;
return a >= 0 ? a / b : (a - b + 1) / b;
}
template<class T>
T ceilDiv(T a, T b) {
if (b < 0) a *= -1, b *= -1;
return a >= 0 ? (a + b - 1) / b : a / b;
}
template<class T> bool chmin(T &a, T b) { return a > b ? a = b, 1 : 0; }
template<class T> bool chmax(T &a, T b) { return a < b ? a = b, 1 : 0; }
#line 1 "modint/dynamicMontgomeryModInt.cpp"
//reference: https://github.com/NyaanNyaan/library/blob/master/modint/montgomery-modint.hpp#L10
//note: mod should be an odd prime less than 2^30.
template<uint32_t ver>
struct MontgomeryModInt {
using mint = MontgomeryModInt;
using i32 = int32_t;
using u32 = uint32_t;
using u64 = uint64_t;
static u32 mod, n2, r;
static constexpr u32 get_r() {
u32 res = 1, base = mod;
for(i32 i = 0; i < 31; i++)
res *= base, base *= base;
return -res;
}
static constexpr u32 get_mod() {
return mod;
}
static void set_mod(u32 _mod) {
mod = _mod;
n2 = -u64(mod) % mod;
r = get_r();
}
u32 a;
static u32 reduce(const u64 &b) {
return (b + u64(u32(b) * r) * mod) >> 32;
}
static u32 transform(const u64 &b) {
return reduce(u64(b) * n2);
}
MontgomeryModInt() : a(0) {}
MontgomeryModInt(const int64_t &b)
: a(transform(b % mod + mod)) {}
mint pow(u64 k) const {
mint res(1), base(*this);
while(k) {
if (k & 1)
res *= base;
base *= base, k >>= 1;
}
return res;
}
mint inverse() const { return (*this).pow(mod - 2); }
u32 get() const {
u32 res = reduce(a);
return res >= mod ? res - mod : res;
}
mint& operator+=(const mint &b) {
if (i32(a += b.a - 2 * mod) < 0) a += 2 * mod;
return *this;
}
mint& operator-=(const mint &b) {
if (i32(a -= b.a) < 0) a += 2 * mod;
return *this;
}
mint& operator*=(const mint &b) {
a = reduce(u64(a) * b.a);
return *this;
}
mint& operator/=(const mint &b) {
a = reduce(u64(a) * b.inverse().a);
return *this;
}
mint operator-() { return mint() - mint(*this); }
bool operator==(mint b) const {
return (a >= mod ? a - mod : a) == (b.a >= mod ? b.a - mod : b.a);
}
bool operator!=(mint b) const {
return (a >= mod ? a - mod : a) != (b.a >= mod ? b.a - mod : b.a);
}
friend mint operator+(mint c, mint d) { return c += d; }
friend mint operator-(mint c, mint d) { return c -= d; }
friend mint operator*(mint c, mint d) { return c *= d; }
friend mint operator/(mint c, mint d) { return c /= d; }
friend ostream& operator<<(ostream& os, const mint& b) {
return os << b.get();
}
friend istream& operator>>(istream& is, mint& b) {
int64_t val;
is >> val;
b = mint(val);
return is;
}
};
using mint = MontgomeryModInt<0>;
template<> uint32_t mint::mod = 0;
template<> uint32_t mint::n2 = 0;
template<> uint32_t mint::r = 0;
#line 1 "numtheory/fastFactorize.cpp"
//source: KACTL(https://github.com/kth-competitive-programming/kactl)
ull modmul(ull a, ull b, ull M) {
ll ret = a * b - M * ull(1.L / M * a * b);
return ret + M * (ret < 0) - M * (ret >= (ll)M);
}
ull modpow(ull b, ull e, ull mod) {
ull ans = 1;
for (; e; b = modmul(b, b, mod), e /= 2)
if (e & 1) ans = modmul(ans, b, mod);
return ans;
}
bool isPrime(ull n) {
if (n < 2 || n % 6 % 4 != 1) return (n | 1) == 3;
ull A[] = {2, 325, 9375, 28178, 450775, 9780504, 1795265022},
s = __builtin_ctzll(n-1), d = n >> s;
for (ull a : A) { // ^ count trailing zeroes
ull p = modpow(a%n, d, n), i = s;
while (p != 1 && p != n - 1 && a % n && i--)
p = modmul(p, p, n);
if (p != n-1 && i != s) return 0;
}
return 1;
}
ull pollard(ull n) {
static mt19937_64 rng(clock);
uniform_int_distribution<ull> unif(0, n - 1);
ull c = 1;
auto f = [n, &c](ull x) { return modmul(x, x, n) + c % n; };
ull x = 0, y = 0, t = 30, prd = 2, i = 1, q;
while (t++ % 40 || __gcd(prd, n) == 1) {
if (x == y) c = unif(rng), x = ++i, y = f(x);
if ((q = modmul(prd, max(x,y) - min(x,y), n))) prd = q;
x = f(x), y = f(f(y));
}
return __gcd(prd, n);
}
vector<ull> factor(ull n) {
if (n == 1) return {};
if (isPrime(n)) return {n};
ull x = pollard(n);
auto l = factor(x), r = factor(n / x);
l.insert(l.end(), r.begin(), r.end());
return l;
}
#line 1 "combi/chromaticNumber.cpp"
//#include "modint/dynamicMontgomeryModInt.cpp"
//#include "numtheory/fastFactorize.cpp"
template<> uint32_t MontgomeryModInt<123>::mod = 0;
template<> uint32_t MontgomeryModInt<123>::n2 = 0;
template<> uint32_t MontgomeryModInt<123>::r = 0;
int chromatic_number(vector<vector<bool>> g) {
const int n = ssize(g);
mt19937 rng(clock);
uniform_int_distribution<int> unif(1 << 29, 1 << 30);
int p = 4;
while(!isPrime(p)) p = unif(rng);
using Mint = MontgomeryModInt<123>;
Mint::set_mod(p);
vector<Mint> I(1 << n);
I[0] = 1;
for(unsigned msk = 1; msk < (1 << n); msk++) {
int v = countr_zero(bit_floor(msk));
I[msk] = I[msk ^ (1 << v)];
unsigned msk2 = msk ^ (1 << v);
for(int x = 0; x < n; x++)
if (g[v][x] and (msk2 >> x & 1))
msk2 ^= 1 << x;
I[msk] += I[msk2];
}
auto check = [&](int c) {
if (c == n) return true;
Mint cnt = 0;
for(unsigned msk = 0; msk < (1 << n); msk++)
cnt += I[msk].pow(c) * (popcount(msk ^ ((1 << n) - 1)) % 2 == 1 ? -1 : 1);
return cnt != 0;
};
int c = 1;
while(!check(c)) c++;
return c;
}
#line 7 "test/chromatic_number.test.cpp"
signed main() {
ios::sync_with_stdio(false), cin.tie(NULL);
int n, m; cin >> n >> m;
vector g(n, vector<bool>(n, false));
for(int i = 0; i < m; i++) {
int u, v; cin >> u >> v;
g[u][v] = g[v][u] = true;
}
cout << chromatic_number(g) << '\n';
return 0;
}