#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

typedef long long ll;
//const int INF = 2e9;
//const ll INF = 9e18;


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

    return 0;
}