fn.cpp
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<cctype>
#include<climits>
#include<algorithm>
#include<utility>
#include<string>
#include<deque>
#include<list>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<vector>
using namespace std;
#define REP(i,N) for (int i = 0; i < (N); i++)
#define FOR(i,a,b) for (int i = (a); i <= (b); i++)
#define FORI(i,a,b) for (int i = (a); i < (b); i++)
#define FORD(i,a,b) for (int i = (a)-1; i >= (b); i--)
#define DP(arg...) fprintf(stderr, ## arg)
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
int N,M;
//vector<int> E[11000];
int deg[11000];
void solve() {
REP(i,N) deg[i] = 0;
REP(i,M) { int a,b;
scanf("%d%d", &a, &b); deg[a-1]++; deg[b-1]++;
}
REP(i,N) { if (deg[i] >= 4) { printf("YES\n"); return; } }
printf("NO\n");
}
int main() {
while (scanf("%d%d", &N, &M) != EOF) {
solve();
}
return 0;
}