#include <string>
#include <vector>
#include <algorithm>

using namespace std;


int find(string number, int start, int end)
{
	int max = start;
	for(int i=start; i<=end; i++)
		max = number[max] < number[i] ? i : max;
	return max;
}


string solution(string number, int k) 
{
	string answer = "";
	int idx = 0;
	for(int j=k; j<number.size(); j++)
	{
		idx = find(number, idx, j);
		answer += number[idx++];
	}
	return answer;
}