#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
using pint = pair<int, int>;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

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