#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <math.h>
#include <iomanip>
#include <map>
using namespace std;

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