#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>

using namespace std;
typedef long long ll;

int __gcd(int x, int y)
{
    if (y == 0) return x;
    return __gcd(y, x % y);
}


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


    return 0;
}