#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define rep(i, a, b) for(int i = a; i < b; i++)
const int mod = 1e9 + 7;
int main()
{

  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  ll w,s;
  cin>>s>>w;
  if(w>=s)cout<<"unsafe";
  else cout<<"safe";
  

} 