using System;

public class Program

{   

    public static int[] ones_to_right_zeros_left(int[] str)

    {

        return str;

    }

    public static char[] remove_bs(char[] str){

        int n = str.Length;

        int idx = 0;

        int bs_so_far = 0;

        while(idx + bs_so_far < n)

        {           

            if(str[idx + bs_so_far] == 'b')

            {

                str[idx + bs_so_far] = '\0';

                bs_so_far++;

            }

            else

            {

                str[idx] = str[idx + bs_so_far];

                idx++;

            }

        }

        for(int i = 0; i < bs_so_far; i++)

        {

            str[n-i-1] = '\0';

        }

        return str; 

    }

    public static void Main()

    {

        char[] t1 = new char[] {'a', 'a', 'b', 'b', 'c', 'a', 'a', 'b', 'a', 'b'}; // aabbcaabab -> aacaaa

        Console.WriteLine(remove_bs(t1));

        t1 = new char[] {'a', 'a' ,'b', 'b'}; // aabb -> 

        Console.WriteLine(remove_bs(t1));

        t1 = new char[] {'b', 'b', 'a'}; // bba -> a

        Console.WriteLine(remove_bs(t1));   

        t1 = new char[] {'a', 'a', 'a'}; // aaa

        Console.WriteLine(remove_bs(t1));   

        Console.WriteLine("Hello World");

    }

}