#include<bits/stdc++.h>
using namespace std;

int main()
{
	int m_s;//各个位的数
	long long n;
	int k;
	cin >> n;
	cin >> k;
	int m_z=0;
	vector<int>a;
	while (n != 0)
	{
		m_s = n % 10;
		a.push_back(m_s);
		m_z += 1;
		n =n / 10;
	}
	int sum = 0;//留下的数据和
	int m_n=m_z-1;// 最小数所在坐标
	const int m_k=m_z-k;//留下的位数
	for (int i = 0; i < m_k; i++)
	{
		int min = 1e9;//最小数
		int flag = 0;
		for (int j =0; j <=m_n; j++)
		{
			if (a[j] <= min && j >= m_k - i - 1)
			{
				min = a[j];
				flag = j;
			}
		}
		m_n = flag-1;
		sum += min * pow(10, (m_k - i - 1));
	}
	cout << sum;
	return 0;
}