#include <iostream>
#include <string>
#include <map>
#include <vector>
#include <bitset>
#include <iomanip>
#include <deque>

using namespace std;

int main()
{
    int a, b;

    cin >> a >> b;

    if (b >= a) {
        cout << "unsafe" << endl;
    }
    else {
        cout << "safe" << endl;
    }
}
