#include <bits/stdc++.h>
using namespace std;
int main(void) {
  std::map<pair<int, int>, bool> m;
  int a, b;
  for (int i = 0; i < 6; i++) {
    cin >> a >> b;
    if (m[make_pair(a, b)]) {
      cout << "no" << endl;
      return 0;
    }
    m[make_pair(a, b)] = true;
  }
  if (m.size() == 3)
    cout << "yes" << endl;
  else
    cout << "no" << endl;
  return 0;
}
