#include<bits/stdc++.h>
#define mod 1000000007
#define ll long long int
#define ar array
#define mp make_pair
using namespace std;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	int s,w;
	cin>>s>>w;
	if(w>=s)
		cout<<"unsafe";
	else
		cout<<"safe";
	return 0;
}