#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef pair<int,int> pii;
typedef pair<long long,long long> pll;


int main()
{
    int s, w;
    
    cin >> s >> w;
    
    if (w >= s) cout << "unsafe\n";
    else cout << "safe\n";

    return 0;
}

