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

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

int main()
{
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  Main();
  return 0;
}