#include <bits/stdc++.h>
using namespace std;
int main() {
  pair<int, int> p[6];
  for (int i = 0; i < 6; ++i) {
    cin >> p[i].first >> p[i].second;
    if (p[i].first > p[i].second) swap(p[i].first, p[i].second);
  }
  sort(p, p + 6);
  if (!(p[0].first == p[1].first && p[0].second == p[1].second)) {
    cout << "no" << endl;
    return 0;
  }
  if (!(p[2].first == p[3].first && p[2].second == p[3].second)) {
    cout << "no" << endl;
    return 0;
  }
  if (!(p[4].first == p[5].first && p[4].second == p[5].second)) {
    cout << "no" << endl;
    return 0;
  }
  cout << "yes" << endl;
  return 0;
}
