import sys
import os

def file_input():
    f = open('../Beginner_Contest_164/input.txt', 'r')
    sys.stdin = f

def main():
    #file_input()
    S,W=map(int, input().split())

    if S <= W:
        print("unsafe")
    else:
        print("safe")

if __name__ == '__main__':
    main()
