using System;
using System.Collections.Generic;
class Program{
  static void Main(){
 
int S=int.Parse(Console.ReadLine());
    int Sh[]=S.Split(' ');
//int W=int.Parse(Console.ReadLine());
 //Console.ReadLine().Split(blank.ToCharArray());
if(Sh[0]>Sh[1])
{
  Console.WriteLine("safe");
}
else
{
 Console.WriteLine("unsafe");
}
} 
}