Problem:
Problem C:Champernowne Constant

Champernown constant is an irrational number represented in decimal by "0." followed by
concatenation of all positive integers in the increasing order. The first few digits of this constant
are: 0.123456789101112...

Your task is to write a program that outputs the K digits of Chapnernown constant starting at
the N-th place for given two natural numbers K and N.

Input

The input has multiple lines. Each line has two positive integers N and K (N ≤ 109, K ≤ 100)
separated by a space.

The end of input is indicated by a line with two zeros. This line should not be processed.

Output

For each line, output a line that contains the K digits.

Sample Input

4 5
6 7
0 0

Output for the Sample Input

45678
6789101

Solution in JAVA (judge verdict: Wrong Answer)

import java.util.*;
import java.math.*;

class Main{
	public static void main(String[] args){
		Solve s = new Solve();
		s.solve();
	}	
}
class Solve{
	Solve(){}
	
	Scanner in = new Scanner(System.in);



	void solve(){
		while(in.hasNext()){
			int n = in.nextInt(), m = in.nextInt();
			if(n == 0 && m == 0) return;
			StringBuilder sb = new StringBuilder();
			for(int i = n; sb.length()<m; i++){
				sb.append(String.valueOf(i));
			}

			String s = sb.toString();
			s = s.substring(0, m);

			System.out.println(s);
		}
	}


	
}

// while(in.hasNext()){
		// 	int n = in.nextInt();
		// 	if(n == 0) return;
			
		// }