#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
int main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
//  #ifdef ONLINE_JUDGE
//	    freopen("input1.txt","r",stdin);
//	    freopen("output1.txt","w",stdout);
//  #endif
    int s , w;
    cin >> s >>w;
    if(w >=s){
    	cout <<"unsafe" <<'\n';
	}
	else
	{
		cout << "safe" <<'\n';
	}

  }
