#include <algorithm>
#include <cmath>
#include <iostream>
#include <queue>
#include <string>
#include <vector>

using ll = long long;
#define rep(inc, bgn, end) for (int inc = bgn; inc < end; ++inc)
#define repe(inc, bgn, end) for (int inc = bgn; inc <= end; ++inc)

using namespace std;

// 151-d
int main() {
    int s, w;
    if (s <= w)
        cout << "unsafe" << endl;
    else
        cout << "safe" << endl;
    return 0;
}