#include<iostream>
#include<numeric>
#include<vector>
#include<iomanip>
#include<algorithm>
#include<map>
#include<utility>
#include<cmath>
#include<tuple>
#include<string>
#include<bitset>
#include<set>
#include<queue>
#include<stack>
#include<cstdio>
using namespace std;
typedef long long ll;

int main(){
    int s,w; cin>>s>>w;
    if(w>=s) cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;
}