
f=0
    # n=int(input())
    # a=list(map(int,input().split()))
    # c,d=map(int,input().split())
    
    s,w=map(int,input().split())
    if(s<=w):
        print("unsafe")
    else:
        print("safe")
    




# print("Yes" if f==1 else "No")