INT_MAX=10**11+7
MOD=10**9+7
def INPUT():return list(int(i) for i in input().split())
def LIST_1D_ARRAY(n):return [0 for _ in range(n)]
def LIST_2D_ARRAY(m,n):return [[0 for _ in range(n)]for _ in range(m)]
#=======================================================================
s,w=INPUT()
if w>=s:
    print("unsafe")
else:print("safe")
