#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
using namespace std;
int main(){
  int a,b;
  cin >> a >> b;
  if(a>b) cout << "safe" << endl;
  else cout << "unsafe" << endl;
}