#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<pair<int, int> > v;
  for (int i = 0; i < 6; i++) {
    int a, b;
    cin >> a >> b;
    v.push_back(make_pair(max(a, b), min(a, b)));
  }
  sort(v.begin(), v.end());
  if (v[0] == v[1] && v[2] == v[3] && v[4] == v[5])
    cout << "yes" << endl;
  else
    cout << "no" << endl;
  return 0;
}
