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

//#define int long long int
const int N=1e3;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(NULL);

	#ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
	#endif

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

	return 0;
}