#include <stdio.h>

int main()
{
	int i, N, A[6];
	scanf("%d", &N);
	for (i = 0; i < 6; i++) scanf("%d", &(A[i]));
	if (N <= 2 || A[0] != A[1] || A[1] == A[2] || A[2] == A[3] || A[2] == A[4] || A[0] == A[5] || A[2] == A[5]) printf("NO\n");
	else printf("YES\n");
	fflush(stdout);
	return 0;
}