#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;++i)
#define rrep(i,n) for(int i=n-1;i>=0;--i)
#define yesno(flg) if(flg){cout<<"yes"<<endl;}else{cout<<"no"<<endl;}
#define vi vector<int>
#define MAX_N 200005
#define i197 1000000007

using namespace std;


typedef long long ll;
typedef pair<int,int> Pi;
typedef pair<ll,ll> P1;
typedef pair<int,P1> P2;
const int inf=1000000000;
P1 xy[MAX_N]={};


int main() {
	Pi hw[6];
	int h1,w1;

	rep(i,6){
		cin>>h1>>w1;
		if(h1>w1)swap(h1,w1);
		hw[i].first=h1;
		hw[i].second=w1;
	}
	sort(hw,hw+6);
	bool flg=true;
	if(hw[0]!=hw[1]||hw[2]!=hw[3])flg=false;
	if(hw[4]!=hw[5]||hw[0].first!=hw[2].first)flg=false;
	if(hw[0].second!=hw[4].first||hw[2].second!=hw[4].second)flg=false;


	if(flg){
		cout<<"yes"<<endl;
	}else{
		cout<<"no"<<endl;
	}


	return 0;
}

