#include <iostream>
#include <vector>
#include <bitset>
#include <utility>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
 
using namespace std;
typedef long long ll;
 
int main(){

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