#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
const long long MOD = 1e9 + 7;
const double pi = acos(-1);
const int SIZE = 1 << 17;
int dx[] = {1, 0}, dy[] = {0, 1}, alp[30];
long long fac[200005], finv[200005], inv[200005];
vector<long long> dij;
struct edge {
  long long to, cost;
};
vector<vector<edge>> G;
long long mod_pow(long long a, long long b) {
  long long res = 1;
  while (b) {
    if (b & 1) {
      res = res * a % MOD;
    }
    a = a * a % MOD;
    b >>= 1;
  }
  return res;
}
void addedge(int from, int to, int cost) {
  G[from].push_back({to, cost});
  G[to].push_back({from, cost});
}
string ans = "no";
int main() {
  vector<pair<int, int>> v;
  for (int i = 0; i < 6; ++i) {
    int a, b;
    cin >> a >> b;
    if (a > b) {
      swap(a, b);
    }
    v.push_back(make_pair(a, b));
  }
  sort(v.begin(), v.end());
  if (v[0] == v[1] && v[2] == v[3] && v[4] == v[5] &&
      v[0].first == v[2].first && v[2].second == v[4].second &&
      v[0].second == v[4].first) {
    ans = "yes";
  }
  cout << ans << endl;
}
