#include<bits/stdc++.h>
using namespace std;
#define loop(i,x,z) for (int i=x;i<z;i++)
using ll = long long;
const int M = 1000000007;
int n, m, k, ans = 0;
int A[1002];
int main()
{
    cin >> n >> m;
    if (m >= n) cout << "unsafe";
    else cout << "safe";
}
