#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n, m, i, j;
  cin >> n >> m;
  vector<pair<long long int, long long int>> vec;
  for (i = 0; i < m; i++) {
    long long int a, b;
    cin >> a >> b;
    vec.push_back({a, b});
  }
  long long int a = vec[0].first;
  long long int f = 0;
  for (i = 1; i < m; i++) {
    long long int x, y;
    x = vec[i].first;
    y = vec[i].second;
    if (x != a && y != a) {
      long long int b = vec[i].first;
      for (j = i + 1; j < m; j++) {
        long long int xt, yt;
        xt = vec[j].first;
        yt = vec[j].second;
        if (xt != a && xt != b && yt != a && yt != b) {
          break;
        }
      }
      if (j >= m) {
        cout << "YES\n";
        return;
      }
      b = vec[i].second;
      for (j = i + 1; j < m; j++) {
        long long int xt, yt;
        xt = vec[j].first;
        yt = vec[j].second;
        if (xt != a && xt != b && yt != a && yt != b) {
          break;
        }
      }
      if (j >= m) {
        cout << "YES\n";
        return;
      }
      f = 1;
    }
    if (f) break;
  }
  if (i >= m) {
    cout << "YES\n";
    return;
  }
  a = vec[0].second;
  f = 0;
  for (i = 1; i < m; i++) {
    long long int x, y;
    x = vec[i].first;
    y = vec[i].second;
    if (x != a && y != a) {
      long long int b = vec[i].first;
      for (j = i + 1; j < m; j++) {
        long long int xt, yt;
        xt = vec[j].first;
        yt = vec[j].second;
        if (xt != a && xt != b && yt != a && yt != b) {
          break;
        }
      }
      if (j >= m) {
        cout << "YES\n";
        return;
      }
      b = vec[i].second;
      for (j = i + 1; j < m; j++) {
        long long int xt, yt;
        xt = vec[j].first;
        yt = vec[j].second;
        if (xt != a && xt != b && yt != a && yt != b) {
          break;
        }
      }
      if (j >= m) {
        cout << "YES\n";
        return;
      }
      f = 1;
    }
    if (f) break;
  }
  if (i >= m) {
    cout << "YES\n";
    return;
  }
  cout << "NO\n";
}
int main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(NULL);
  int t;
  t = 1;
  while (t > 0) {
    t--;
    solve();
  }
}
