#include <bits/stdc++.h>
#define MAXN 100010
#define pii pair<int,int>
#define ff first
#define ss second
#define ll long long
#define in_range(x, y, n) (x >= 0 and x<n and y >=0 and y<n)
using namespace std;
const int mod = 1e9 + 7;

int main (){
    int a, b;

    cin >> a >> b;

    cout << (a>b? "safe" : "unsafe") << endl;
}