#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1000000007;
int main()
{
    int s,w;
    cin >> s >> w;
    if(w >= s)
    {
        cout << "unsafe\n";
    }
    else
    {
        cout << "safe\n";
    }
    
    return 0;
}