#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	double a,b;
	cin>>a>>b;
	if(b>=a/2.0){
		cout<<"unsafe"<<endl;
	}else{
		cout<<"safe"<<endl;
	}
}
