#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#define ll long long int
#define MOD 1000000007
using namespace std;

int main() {
	int a,b;
	cin>>a>>b;
	if(a>b) cout <<"safe"<<endl;
	else cout <<"unsafe"<<endl;

	return 0;
}
