import math
import collections


def main():
    s, w = input_list()
    if w >= s:
        print('unsafe')
    else:
        print('safe')


def input_list():
    return list(map(int, input().split()))


def combinations_count(n, r):
    return math.factorial(n) // (math.factorial(n - r) * math.factorial(r))


if __name__ == '__main__':
    main()
