#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> v;
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    v.push_back(make_pair(a, b));
  }
  int x1 = v[0].first;
  int y1 = v[0].second;
  vector<int> p1, p2;
  for (int i = 1; i < m; i++) {
    int a = v[i].first;
    int b = v[i].second;
    if (x1 != a && x1 != b) {
      p1.push_back(i);
    }
    if (y1 != a && y1 != b) {
      p2.push_back(i);
    }
  }
  if (p1.size() == 0 || p2.size() == 0) {
    cout << "YES" << endl;
    return 0;
  }
  x1 = v[p1[0]].first;
  y1 = v[p1[0]].second;
  int c1 = 0, c2 = 0, c3 = 0, c4 = 0;
  for (int i = 1; i < p1.size(); i++) {
    int a = v[p1[i]].first;
    int b = v[p1[i]].second;
    if (x1 != a && x1 != b) {
      c1++;
    }
    if (y1 != a && y1 != b) {
      c2++;
    }
  }
  x1 = v[p2[0]].first;
  y1 = v[p2[0]].second;
  for (int i = 1; i < p2.size(); i++) {
    int a = v[p2[i]].first;
    int b = v[p2[i]].second;
    if (x1 != a && x1 != b) {
      c3++;
    }
    if (y1 != a && y1 != b) {
      c4++;
    }
  }
  if (c1 == 0 || c2 == 0) {
    cout << "YES" << endl;
  } else if (c3 == 0 || c4 == 0) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
  return 0;
}
