#include<bits/stdc++.h>
#define lowbit(x) x & (-x)
#define ls(k) k << 1
#define rs(k) k << 1 | 1
#define fi first
#define se second
#define ctz(x) __builtin_ctz(x)
#define popcnt(x) __builtin_popcount(x)
#define open(s1, s2) freopen(s1, "r", stdin), freopen(s2, "w", stdout);
using namespace std;
typedef __int128 __;
typedef long double lb;
typedef double db;
typedef unsigned long long ull;
typedef long long ll;
bool Begin;
const int N = 2e4 + 10;
inline ll read(){
    ll x = 0, f = 1;
    char c = getchar();
    while(c < '0' || c > '9'){
        if(c == '-')
          f = -1;
        c = getchar();
    }
    while(c >= '0' && c <= '9'){
        x = (x << 1) + (x << 3) + (c ^ 48);
        c = getchar();
    }
    return x * f;
}
inline void write(ll x){
	if(x < 0){
		putchar('-');
		x = -x;
	}
	if(x > 9)
	  write(x / 10);
	putchar(x % 10 + '0');
}
int n, m, u, v;
vector<int> E[N], V[N];
inline void add(int u, int v){
	E[u].push_back(v);
	E[v].push_back(u);
}
bool End;
int main(){
	n = read(), m = read();
	while(m--){
		u = read(), v = read();
		add(u, v);
	}
	for(auto u : E[1]){
		for(auto v : E[u]){
			if(v == 1)
			  continue;
			if((int)V[v].size() < 3)
			  V[v].push_back(u);
		}
	}
    for(int i = 2; i <= n; ++i){
        for(int v : E[i]){
            for(int j = 0; j < V[i].size(); ++j){
				for(int k = 0; k < V[v].size(); ++k){
	                if(V[i][j] != v && V[i][j] != V[v][k] && V[v][k] != i){
	                    puts("YES");
	                    return 0;
	                }
            	}
			}
        }
    }
    puts("NO");
	cerr << '\n' << abs(&Begin - &End) / 1048576 << "MB";
	return 0;
}