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