#include <bits/stdc++.h>
using namespace std;

void solved()
{
    int s,w;
    cin >> s >> w;
    if(w >= s)cout <<"unsafe";
    else cout <<"safe";
}

int main()
{
#ifdef ONLINE_JUEDGE
    ios::sycn_with_stdio(false);cin.tie(0);cout.tie(0);
#endif
    int t = 1;
    //cin >> t;
    while(t--)
    {
        solved();
    }



#ifndef ONLINE_JUEDGE
    system("pause");
#endif 
    return 0;
}