Lucky Strings : Lucky numbers are those numbers which contain only "4" and/or "5". For example 4, 5, 44, 54,55,444 are lucky numbers while 457, 987 ,154 are not. Lucky number sequence is one in which all lucky numbers exist in increasing order for example 4,5,44,45,54,55,444,445,454,455... Now we concatenate all the lucky numbers (in ascending o…

Lucky Strings

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;

public class LuckyStrings {

	public static void main(String args[]) throws NumberFormatException, IOException
	{
		
		  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		  int N = Integer.parseInt(br.readLine());
			if(N == 4)
				System.out.println("Hacker");
			else
				System.out.println("Earth");
		}
	}

	public static int getNthDigit(long n)
	{
		if(n == 1)
			return 4;
		if(n == 2)
			return 5;
		int curDigit = 1;
		long totalFoundDigits = 2;
		int nextTotalDigits = 0;
		while(true){
			nextTotalDigits = (int) ((curDigit+1)*Math.pow(2, curDigit+1 ));
			
			if(totalFoundDigits + nextTotalDigits <= n){
				totalFoundDigits += nextTotalDigits;
				curDigit++;
			}
			else{
				break;
			}

		}
		
		//System.out.println("totalFound "+totalFoundDigits +" "+n );
		return getNumber(curDigit+1,(int) ((n- totalFoundDigits - 1)/(curDigit+1)),(int) (n- totalFoundDigits)%(curDigit+1));
	}

	private static int getNumber(int noOfDigits, int number, int digit)
	{
		if(digit == 0) digit = noOfDigits-1 ;
		else digit--;
		//System.out.println("Params "+noOfDigits+" "+number+" "+digit);
		int[] no = new int[noOfDigits];
		Arrays.fill(no, 4);
		int index = no.length-1;
		while(number > 0)
		{
			int val = number%2;
			if(val == 0)
				no[index--] = 4;
			else
				no[index--] = 5;
			number /= 2;
		}
		//System.out.println(Arrays.toString(no));
		return no[digit];
	}

}