#include <bits/stdc++.h>
using namespace std;
int main(void) {
  vector<pair<int, int> > v;
  for (int i = 0; i < 6; i++) {
    int h, w;
    cin >> h >> w;
    if (h < w) swap(h, w);
    v.push_back(make_pair(h, w));
  }
  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;
}
