#include <bits/stdc++.h>

using namespace std;
typedef long long lint;

#define RPT(i, b, e) for (int i = ((int)b); i <= ((int)e); i++)
#define RPT0(i, n) RPT(i, 0, ((int)n) - 1)
#define RPT1(i, n) RPT(i, 1, (n))
#define EACH(it, v) for (const auto& it : v)
#define ALL(v) v.begin(), v.end()

void resolve()
{
    int S, W;
    cin >> S >> W;

    cout << (W >= S ? "unsafe" : "safe") << endl;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    resolve();
    return 0;
}
