#include <bits/stdc++.h>

using namespace std;

#define intt long long
#define FAST ios_base::sync_with_stdio(0); cin.tie(0);

const int N = 100005;

int n;
int a[N];

int main() {

    FAST;

    int s, w;
    cin >> s >> w;
    if (w >= s) cout << "unsafe\n";
    else cout << "safe\n";
    return 0;
}
