#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m;
  cin >> n >> m;
  pair<long long, long long> p[m];
  long long toe[2] = {-1, -1};
  for (long long i = 0; i < m; i++) {
    cin >> p[i].first >> p[i].second;
    if (i > 0) {
      if (p[i].first != p[0].first && p[i].first != p[0].second &&
          p[i].second != p[0].first && p[i].second != p[0].second) {
        toe[0] = p[i].first;
        toe[1] = p[i].second;
      }
    }
  }
  if (toe[0] == -1) {
    cout << "YES" << endl;
    return 0;
  }
  long long a = p[0].first;
  long long b = toe[0];
  bool a1 = true;
  for (long long i = 0; i < m; i++) {
    if (p[i].first == a || p[i].second == a || p[i].first == b ||
        p[i].second == b) {
      ;
    } else {
      a1 = false;
      break;
    }
  }
  long long c = toe[1];
  bool a2 = true;
  for (long long i = 0; i < m; i++) {
    if (p[i].first == a || p[i].second == a || p[i].first == c ||
        p[i].second == c) {
      ;
    } else {
      a2 = false;
      break;
    }
  }
  a = p[0].second;
  bool a3 = true;
  for (long long i = 0; i < m; i++) {
    if (p[i].first == a || p[i].second == a || p[i].first == c ||
        p[i].second == c) {
      ;
    } else {
      a3 = false;
      break;
    }
  }
  bool a4 = true;
  for (long long i = 0; i < m; i++) {
    if (p[i].first == a || p[i].second == a || p[i].first == b ||
        p[i].second == b) {
      ;
    } else {
      a4 = false;
      break;
    }
  }
  if (a1 || a2 || a3 || a4)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
