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

int main() {
  long long n,w,sum=0, mod=2019;
  cin>>n>>w;
  
  if(n<=w)
    cout<<"unsafe"<<endl;
  else
    cout<<"safe"<<endl;
}

