#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
#define rep(begin, i, end) for (int i = begin; i < (int)(end); i++)
#define all(v) v.begin(), v.end()
const int MOD = 1000000007;

int main()
{
    int S, W;
    cin >> S >> W;
    if (S > W)
    {
        cout << "safe" << endl;
    }
    else
    {
        cout << "unsafe" << endl;
    }
}