#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define Mod 1000000007
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

int main()
{
    fastio;
    
		ll s, w;
		cin >> s >> w;
		
		if (s > w)
			cout << "safe\n";
		else
			cout << "unsafe\n";
	//code
	return 0;
}
