#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main()
{
    int s, w;
    cin >> s >> w;
    if (s <= w) cout << "unsafe" << endl;
    else cout << "safe" << endl;
    
    return 0;
}