#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const ll INF = 1LL << 60;

int main() {
    int S, W;
    cin >> S >> W;
    if (W >= S) {
        cout << "unsafe" << endl;
    } else {
        cout << "safe" << endl;
    }

    return 0;
}