#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.precision(10);
ll w,s;
    cin>>s>>w;
    if(s>w)
    {
        cout<<"safe";
    }
    else cout<<"unsafe"<<endl;
    // cout << fixed;
    return 0;
}