225A - Dice Tower - CodeForces Solution

'''Author : seraph14'''
import sys, io, os
import heapq
if 'PyPy' in sys.version:
    from _continuation import continulet
else:
    import threading
input = sys.stdin.readline

hqp = heapq.heappop
hqs = heapq.heappush

def _print(*argv, sep=" "):
    sys.stdout.write(sep.join(map(str, argv)) + "\n")

def inp():
    return (int(input()))

def inlt():
    return (list(map(int, input().split())))

def insr():
    if input == sys.stdin.readline:
        s = input()
        return list(s.strip())
    else:
        s = input().decode()
        return (list(s[:len(s)-2]))

def invr():
    return (map(int, input().split()))

def get_bool(right):
    return "YES" if right else "NO"

def solve():
    pass

def main():
    n = inp()
    can = True
    x = inp()
    candidates = set(range(1, 7))
    candidates.discard(7-x)

    for _ in range(n):
        a, b = invr()
        if not can:
            continue
        for c in [a, b, 7-a, 7-b]:
            candidates.discard(c)
        can &= len(candidates) == 1
        top = candidates.pop() if candidates else x
        candidates = set(range(1, 7))
        candidates.discard(7-top)
    
    _print(get_bool(can))


if __name__ == '__main__':
    if 'PyPy' in sys.version:

        def bootstrap(cont):
            call, arg = cont.switch()
            while True:
                call, arg = cont.switch(
                    to=continulet(lambda _, f, args: f(*args), call, arg))
        cont = continulet(bootstrap)
        cont.switch()
        main()
    else:
        sys.setrecursionlimit(1 << 30)
        threading.stack_size(1 << 27)

        main_thread = threading.Thread(target=main)
        main_thread.start()
        main_thread.join()