#include <bits/stdc++.h>
using namespace std;
int a[6];
int main() {
  for (int b = 0; b < 6; b++) {
    int c, d;
    cin >> c >> d;
    a[b] = min(c, d) + max(c, d) * 10000;
  }
  sort(a, a + 6);
  if (a[0] == a[1] && a[2] == a[3] && a[4] == a[5])
    puts("yes");
  else
    puts("no");
}
