#include <bits/stdc++.h>
using namespace std;
using lint = long long;
struct pre_ {
  pre_() {
    cin.tie(0);
    ios::sync_with_stdio(0);
  }
} pre__;
signed main() {
  pair<int, int> p[6];
  for (lint i = (0); i < (lint)(6); ++i) cin >> p[i].first >> p[i].second;
  for (lint i = (0); i < (lint)(6); ++i) {
    if (p[i].first > p[i].second) {
      swap(p[i].first, p[i].second);
    }
  }
  sort(p, p + 6);
  cout << (p[0] == p[1] && p[2] == p[3] && p[4] == p[5] ? "yes" : "no") << endl;
}
