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