#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0;i < (n);i++)
using ll = long long;
const ll MOD=1000000007;



int main() {
  ll S,W;
  cin>>S>>W;
  if(W>=S)
  {
    cout<<"unsafe"<<endl;
  }
  else
  {
    cout<<"safe"<<endl;
  }
  
  return 0;
}
