#include <bits/stdc++.h>
using namespace std;
int co[500005] = {0};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, m, x, y;
  cin >> n >> m;
  int maxi = 0, in = -1;
  map<pair<int, int>, int> ma;
  for (int i = 0; i < m; i++) {
    cin >> x >> y;
    ma[{min(x, y), max(x, y)}]++;
    co[x]++;
    co[y]++;
    if (co[x] > maxi) {
      maxi = co[x];
      in = x;
    }
    if (co[y] > maxi) {
      maxi = co[y];
      in = y;
    }
  }
  int f = 0;
  vector<pair<int, int> > v;
  for (int i = 1; i <= n; i++) {
    if (co[i] > 0) {
      v.push_back({co[i], i});
    }
  }
  sort(v.begin(), v.end());
  for (int i = v.size() - 1; i >= 0; i--) {
    for (int j = i - 1; j >= 0; j--) {
      if (v[j].first + v[i].first -
              ma[{min(v[j].second, v[i].second),
                  max(v[j].second, v[i].second)}] >=
          m) {
        f = 1;
        break;
      }
      if (v[j].first < m - v[i].first) break;
    }
    if (f) break;
    if (v[i].first < (m / 2)) break;
  }
  if (f)
    cout << "YES\n";
  else
    cout << "NO\n";
  return 0;
}
