#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
#include<ios>//左右揃え
#include<iomanip>//setwで幅指定

using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
#define MOD 1000000007LL

int main(void) {
    int s, w;
    cin >> s >> w;
    s <= w ? cout << "unsafe" << endl : cout << "safe" << endl;
}