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

print((["safe","unsafe"][w>=s]))
s,w=list(map(int,input().split()));print((["","un"][w>=s]+"safe"))
s, w = list(map(int, input().split()))
print((["safe", "unsafe"][w >= s]))

s, w = list(map(int, input().split()))
print((["", "un"][w >= s] + "safe"))

-print((["safe", "unsafe"][w >= s])) +print((["", "un"][w >= s] + "safe"))