#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll,ll>
#define vpll vector <pll>
#define pb push_back

int main()
{
   int s,w;
   cin>>s>>w;
   if(s<w)
    cout<<"safe";
   else
    cout<<"unsafe";
    return 0;
}
