#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define FAST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(0);
using namespace std;

int main()
{
   int t;t=1;
   FAST
   while(t--)
   {
       int n,k;cin>>n>>k;
       cout<<(n<k ? "unsafe\n":"safe\n");
   }
}