// template.cpp {{{
#include <bits/stdc++.h>
using namespace std;

using lint = long long;
#define reps(i, a, n) for (lint i = (a); i < (lint)(n); ++i)
#define rep(i, n) reps(i, 0, n)
struct pre_{pre_(){cin.tie(0);ios::sync_with_stdio(0);}} pre__;
// }}}

#define fi first
#define se second

signed main() {
  pair<int, int> p[6];
  rep(i, 6) cin >> p[i].fi >> p[i].se;
  rep(i, 6) {
    if (p[i].fi > p[i].se) {
      swap(p[i].fi, p[i].se);
    }
  }
  sort(p, p + 6);

  if (p[0] != p[1] || p[2] != p[3] || p[4] != p[5]) {
    cout << "no" << endl;
  } else if (p[0].fi != p[2].fi || p[0].se != p[4].fi) {
    cout << "no" << endl;
  } else if (p[2].se != p[4].se) {
    cout << "no" << endl;
  } else {
    cout << "yes" << endl;
  }
}