#include <iostream>
using namespace std;
int main()
{
bool possible(true);
int n, x, a, b;
cin >> n >> x;
while (n--)
{
cin >> a >> b;
if (x == a || x == b || x == 7 - a || x == 7 - b)
{
possible = false;
}
x = 7 - x;
}
cout << (possible ? "YES" : "NO") << endl;
return 0;
}
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