#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=int(a);i<int(b);i++)
typedef long long ll;


int main(){
    ll n,m;cin>>n>>m;
    if(n<=m)cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;
    
}
    







