#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define MAX 300003
#define MOD 1000000007
#define INF 1000000000000000

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