import sys



sys.setrecursionlimit(10 ** 7)

rl = sys.stdin.readline





def solve():

    s, w = list(map(int, rl().split()))

    if s > w:

        print('safe')

    else:

      print('unsafe')

    



if __name__ == '__main__':

    solve()

def solve():

    S, W = list(map(int,input().split()))

    if S > W:

        print("safe")

    else:

        print("unsafe")

    



if __name__ == '__main__':

    solve()

import sys

sys.setrecursionlimit(10**7)
rl = sys.stdin.readline


def solve():
    s, w = list(map(int, rl().split()))
    if s > w:
        print("safe")
    else:
        print("unsafe")


if __name__ == "__main__":
    solve()

def solve():
    S, W = list(map(int, input().split()))
    if S > W:
        print("safe")
    else:
        print("unsafe")


if __name__ == "__main__":
    solve()

-import sys - -sys.setrecursionlimit(10**7) -rl = sys.stdin.readline - - -    s, w = list(map(int, rl().split())) -    if s > w: +    S, W = list(map(int, input().split())) +    if S > W: