/*
 * @Author: Luisvacson
 * @LastEditors: Luisvacson
 * @Descriptions: None
 * @Date: 2020-04-26 20:01:09
 * @LastEditTime: 2020-04-26 20:02:13
 * @FilePath: \VSC\C++\Practice\AC abc164 A.cpp
 */
#include<bits/stdc++.h>
using namespace std;

int x,y;
signed main(){
    scanf("%d%d",&x,&y);
    puts(x<=y?"unsafe":"safe");
    return 0;
}