import java.util.Scanner;
public class Main
{
    public static void Main(String args[])
    {
        Scanner sc=new Scanner(System.in);
        String s=sc.nextLine();
    
        if(!sc.hasNextInt())
        {
            System.out.println("true");
        }
        
        else
        {
            System.out.println("false");
        }
        
    }
}