#include <iostream>
#include <string>
#include <cstdio>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <functional>

using namespace std;


void solve(long long S, long long W){

}

// Generated by 1.1.6 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
int main(){
    long long S;
    scanf("%lld",&S);
    long long W;
    scanf("%lld",&W);
    
    if(W>=S){
        cout<<"unsafe"<<endl;
    }else{
        cout<<"safe"<<endl;
    }

    return 0;
}
