#include<cstdio>
#include <iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>

using namespace std;
typedef long long ll;
typedef pair<int, int>P;

int main(void)
{
	P D[6];
	for (int i = 0; i < 6; i++) {
		cin >> D[i].first >> D[i].second;
	    if (D[i].first > D[i].second)swap(D[i].first, D[i].second);
	}
	int flag = 0;
	sort(D,D+6);
	for (int i = 0; i < 6; i += 2) {
		if (D[i] == D[i + 1])D[i / 2] = D[i];
		else {
			flag = 1;
			cout << "no" << endl;
			break;
		}
	}
	if (!flag) {
		if (D[0].first == D[1].first && D[0].second == D[2].first && D[1].second == D[2].second)
			cout << "yes" << endl;
		else
			cout << "no" << endl;
	}
	return 0;
}