#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <cassert>
using namespace std;

#define GET_ARG(a,b,c,F,...) F
#define REP3(i,s,e) for (i = s; i <= e; i++)
#define REP2(i,n) REP3 (i,0,(int)(n)-1)
#define REP(...) GET_ARG (__VA_ARGS__,REP3,REP2) (__VA_ARGS__)
#define RREP3(i,s,e) for (i = s; i >= e; i--)
#define RREP2(i,n) RREP3 (i,(int)(n)-1,0)
#define RREP(...) GET_ARG (__VA_ARGS__,RREP3,RREP2) (__VA_ARGS__)
#define DEBUG(x) cerr << #x ": " << x << endl

vector<int> e[20000];
set<int> s[20000];

int main(void) {
    int i, n, m;
    scanf("%d%d",&n,&m);
    REP (i,m) {
        int a, b;
        scanf("%d%d",&a,&b);
        a--; b--;
        e[a].push_back(b);
        e[b].push_back(a);
    }
    for (auto x: e[0]) for (auto y: e[x]) if (y != 0) {
        s[y].insert(x);
    }
    bool ans = false;
    REP (i,n) for (auto x: e[i]) if (x != 0) {
        bool bi = s[i].count(x), bx = s[x].count(i);
        if (bi) s[i].erase(x);
        if (bx) s[x].erase(i);
        int ni = s[i].size(), nx = s[x].size();
        if (ni == 1 && nx == 1 && *s[i].begin() != *s[x].begin()) ans = true;
        else if ((ni > 1 && nx > 0) || (ni > 0 && nx > 1)) ans = true;
        if (bi) s[i].insert(x);
        if (bx) s[x].insert(i);
    }
    if (ans)
        puts("YES");
    else
        puts("NO");
    return 0;
}