Language: C++

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;
			
		// }

Compiler output:
a.cc:1:1: error: 'import' does not name a type
    1 | import java.util.*;
      | ^~~~~~
a.cc:1:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:2:1: error: 'import' does not name a type
    2 | import java.math.*;
      | ^~~~~~
a.cc:2:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:5:15: error: expected ':' before 'static'
    5 |         public static void main(String[] args){
      |               ^~~~~~~
      |               :
a.cc:5:33: error: 'String' has not been declared
    5 |         public static void main(String[] args){
      |                                 ^~~~~~
a.cc:5:42: error: expected ',' or '...' before 'args'
    5 |         public static void main(String[] args){
      |                                          ^~~~
a.cc:9:2: error: expected ';' after class definition
    9 | }
      |  ^
      |  ;
a.cc: In static member function 'static void Main::main(int*)':
a.cc:6:17: error: 'Solve' was not declared in this scope
    6 |                 Solve s = new Solve();
      |                 ^~~~~
a.cc:7:17: error: 's' was not declared in this scope
    7 |                 s.solve();
      |                 ^
a.cc: At global scope:
a.cc:13:9: error: 'Scanner' does not name a type
   13 |         Scanner in = new Scanner(System.in);
      |         ^~~~~~~
a.cc:35:2: error: expected ';' after class definition
   35 | }
      |  ^
      |  ;
a.cc: In member function 'void Solve::solve()':
a.cc:18:23: error: 'in' was not declared in this scope; did you mean 'int'?
   18 |                 while(in.hasNext()){
      |                       ^~
      |                       int
a.cc:20:38: error: 'm' was not declared in this scope
   20 |                         if(n == 0 && m == 0) return;
      |                                      ^
a.cc:21:25: error: 'StringBuilder' was not declared in this scope
   21 |                         StringBuilder sb = new StringBuilder();
      |                         ^~~~~~~~~~~~~
a.cc:22:40: error: 'sb' was not declared in this scope
   22 |                         for(int i = n; sb.length()<m; i++){
      |                                        ^~
a.cc:22:52: error: 'm' was not declared in this scope
   22 |                         for(int i = n; sb.length()<m; i++){
      |                                                    ^
a.cc:23:43: error: 'String' was not declared in this scope
   23 |                                 sb.append(String.valueOf(i));
      |                                           ^~~~~~
a.cc:26:25: error: 'String' was not declared in this scope
   26 |                         String s = sb.toString();
      |                         ^~~~~~
a.cc:27:25: error: 's' was not declared in this scope
   27 |                         s = s.substring(0, m);
      |                         ^
a.cc:27:44: error: 'm' was not declared in this scope
   27 |                         s = s.substring(0, m);
      |                                            ^
a.cc:29:25: error: 'System' was not declared in this scope
   29 |                         System.out.println(s);
      |                         ^~~~~~