#include <bits/stdc++.h>
class BPairs {
 public:
  void solve(std::istream& in, std::ostream& out) {
    int n, m;
    in >> n >> m;
    std::vector<std::pair<int, int> > pairs(m);
    for (int i = 0; i < m; ++i) {
      int a, b;
      in >> a >> b;
      pairs[i] = std::pair<int, int>(a, b);
    }
    int a = pairs[0].first;
    int b = pairs[0].second;
    int c, d;
    bool found = false;
    for (int i = 1; i < m; ++i) {
      c = pairs[i].first;
      d = pairs[i].second;
      if (c != a && c != b && d != a && d != b) {
        found = true;
        break;
      }
    }
    if (!found) {
      out << "YES";
      return;
    }
    std::vector<std::pair<int, int> > options = {
        std::pair<int, int>(a, c), std::pair<int, int>(a, d),
        std::pair<int, int>(b, c), std::pair<int, int>(b, d)};
    for (auto it = options.begin(); it != options.end(); ++it) {
      a = it->first;
      b = it->second;
      bool ok = true;
      for (int i = 0; i < m; ++i) {
        c = pairs[i].first;
        d = pairs[i].second;
        if (!(a == c || a == d || b == c || b == d)) {
          ok = false;
          break;
        }
      }
      if (ok) {
        out << "YES";
        return;
      }
    }
    out << "NO";
  }
};
int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(NULL);
  std::cout << std::fixed;
  std::cout << std::setprecision(15);
  BPairs solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  solver.solve(in, out);
  return 0;
}
