//入力チェック
#include <iostream>
#include <algorithm>
#include <atcoder/all>
#include <set>
#include <cassert>
using namespace std;
using namespace atcoder;
using ll = long long;
//#define endl "\n";
ll N, M, cnt[4];
vector<ll> G[300009];
set<ll> st[300009];

int main(){
    cin >> N >> M;
    assert(2 <= N && N <= 300000);
    assert(0 <= M && M <= min(N*(N-1)/2, 300000LL));
    for(int i = 0; i < M; i++){
        ll a, b;
        cin >> a >> b;
        assert(st[a].find(b) == st[a].end());
        assert(a < b);
        st[a].insert(b);
        st[b].insert(a);
    }
    return 0;
}