/*
  ->->->->->-> Vora Mahammadasim <-<-<-<-<-<-
*/
#include<bits/stdc++.h>
#include<stdio.h>
#define int long long
#define pb emplace_back
#define Mod 1000000007
#define all(a) a.begin(),a.end()
using namespace std;
signed main(){

    ios::sync_with_stdio(false);
    cin.tie(0);
    int s,w;
    cin>>s>>w;
    if(w >= s) cout<<"unsafe";
    else cout<<"safe";
}
