#include <iostream>
#include <vector>
#include <set>
#include <unordered_set>
#include <map>
#include <algorithm>
#include <string>
#include <math.h>
using namespace std;

#define loop(i,n) for(int i=0;i<n;++i)
typedef long long ll;
typedef string str;

int main ()
{
	int t,n,a,b,k;
cin >> t >>  n;
	if (t > n)
	{
		cout << "safe";
		
	}
	else
	cout << "unsafe";
	return 0;
}

