#include<iostream>
#include <algorithm>
#include<queue>
#include<cmath>
#include<math.h>
#include<string>
#include<string.h>
#include<map>
#include<set>
//#include <Eigen/Dense>
//#include <Eigen/Geometry>
//using namespace Eigen;

using namespace std;




int main() 
{
	int s, w;
	cin >> s >> w;
	if (w >= s)
		cout << "unsafe" << endl;
	else
		cout << "safe" << endl;
	return 0;
}
