#include <bits/stdc++.h>

using namespace std;

const int Nmax = 2e5 + 5;
const int Mod = 1e9 + 7;
const int oo = 2e9;

int s, w;

int main()
{
/**
    #ifndef ONLINE_JUDGE

        ifstream cin("test.in");

    #endif // ONLINE_JUDGE
*/

    cin >> s >> w;

    cout << (w >= s ? "unsafe" : "safe");
    return 0;
}
