#pragma GCC target("avx2")
#pragma GCC optimize("03")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std; typedef long double ld; typedef long long ll;
typedef unsigned long long ull;
#define endl "\n"
#define FOR(i,a,b) for(int i=(a);i<=(b);i++)
#define rep(i,n) for(int i=0;i<(n);i++)
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define ALL(x) (x).begin(), (x).end()
constexpr int INF=1<<30; constexpr ll LINF=1LL<<60; constexpr ll mod=1e9+7; constexpr int NIL = -1;
template<class T>inline bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>inline bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
template<class T>inline int popcount(T a) {return __builtin_popcount(a);}
template<class T>inline T emod(T a, T p) { return (a%p + p) % p;}
//-------------------
constexpr int MX = 502;
int G[MX][MX];
int n,m;

bool dfs(int c, int k) {
    if(k == m) return true;
    bool res = false;
    rep(i, n) {
        if(c==i) continue;
        if(G[c][i]==1) {
            G[c][i] = -1; G[i][c] = -1;
            res |= dfs(i, k+1);
            G[c][i] = 1; G[i][c] = 1;
        }
    }
    return res;
}
int main() {
    cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(15);
    cin >> n >> m;
    rep(i,m) {
        int a,b; cin >> a >> b;
        G[a][b] = 1;
        G[b][a] = 1;
    }
    bool ans = false;
    rep(i, n) {
        ans |= dfs(i, 0);
    }
    if(ans) cout << "YES" << endl;
    else cout << "NO" << endl;
    return 0;
}