#include<bits/stdc++.h>
using namespace std;
#define MOD 1000000007
#define INF 1000000010
#define EPS 1e-9
#define fst first
#define scd second

#define debug(x) cout<<x<<endl;
#define repi(i,x,n) for(int i=x;i<n;i++)
#define rep(i,n) repi(i,0,n)
#define lp(i,n) repi(i,0,n)
#define repn(i,n) for(int i=n;i>=0;i--)
#define int long long
#define endl "\n"


signed main(){
  cin.tie(0);	
  ios::sync_with_stdio(false);
  pair<int,int> a[6];
  rep(i,6){
    cin>>a[i].fst>>a[i].scd;
    if(a[i].fst<a[i].scd) swap(a[i].fst,a[i].scd);
  }
  sort(a,a+6);
  if(a[0]==a[1] && a[2]==a[3] && a[4]==a[5]){
    int x=a[0].fst,y=a[0].scd;
    int x2[2]={a[2].fst,a[2].scd},y2[2]={a[4].fst,a[4].scd};
    rep(i,2){
      rep(j,2){
	if(x==x2[i] && y==y2[j] && x2[1-i]==y2[1-j]){
	  cout<<"yes"<<endl;
	  return 0;
	}
	if(y==x2[i] && x==y2[j] && x2[1-i]==y2[1-j]){
	  cout<<"yes"<<endl;
	  return 0;
	}
      }
    }
  }
	
  cout<<"no"<<endl;
  

  return 0;
}

