#include <bits/stdc++.h>   int n, ust, x, y, mark[10];   int main() {     scanf( %d , &n);     scanf( %d , &ust);     for (int i = 0; i < n; i++) {       scanf( %d %d , &x, &y);       mark[x] = 1;       mark[y] = 1;       mark[7 - x] = 1;       mark[7 - y] = 1;       if (!mark[7 - ust])         for (int j = 0; j < 7; j++) mark[j] = 0;       else {         printf( NO n );         return 0;       }     }     printf( YES n );   }   