t1z3_version1

#include <iostream>
#include <string>
#include <stdio.h>
#include <algorithm>
#include <list>

std::string str;
int c[30];
std::list<int> char_pos[30];

int get_high_char()
{
    int res = 0;
    while(c[res] == 0) res++;
    for(int i = 0; i < 26; i++)
    {
        if(c[i] == 0) continue;
        if(c[res] < c[i]) res = i;
    }
    return res;
}

int get_lower_char()
{
    int res = 0;
    while(c[res] == 0) res++;
    for(int i = 0; i < 26; i++)
    {
        if(c[i] == 0) continue;
        if(c[res] > c[i]) res = i;
    }
    return res;
}

int main()
{
    freopen("input.txt", "rt", stdin);
    freopen("output.txt", "wt", stdout);

    int n, k;
    std::cin >> n >> k;
    std::cin >> str;

    int g = std::min(n, k);
    for(int i = 0; i < n; i++)
    {
        c[str[i] - 'a']++;
        char_pos[str[i] - 'a'].push_front(i);
    }

    if(k >= n - c[get_high_char()])
    {
        int d = get_high_char();
        for(int i = 0; i < n; i++)
        {
            putchar('a' + d);
        }
        return 0;
    }

    for(int i = 0; i < g; i++)
    {
        int hi = get_high_char(), lo = get_lower_char();

        if(std::abs(c[hi] - c[lo]) == 0) break;

        int hi_pos = char_pos[hi].front();
        char_pos[hi].pop_front();
        char_pos[lo].push_front(hi_pos);

        str[hi_pos] = 'a' + lo;

        c[hi]--;
        c[lo]++;
    }

    std::cout << str << std::endl;

    return 0;
}