#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define Rep(i, m,n) for (int i = m; i < (int)(n); i++)

int main(){
int M,N; cin>>M>>N;
  if(M>N){cout<<"safe"<<endl;}
  else {cout<<"unsafe"<<endl;}
}
