#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

char str[1001];
int n,k;
bool killed[1001];

int main()
{
    freopen("letters.in","r",stdin);
    freopen("letters.out","w",stdout);

    int i;
    int ctr;

    scanf("%d %d",&n,&k);

    scanf("%s",str+1);

    sort(str+1,str+1+n);

    ctr=n;

    for (i=n;i>=2;i--)
    {
        if (ctr==k)
        break;

        if (str[i]==str[i-1])
        {
            killed[i]=true;
            ctr--;
        }
    }

    for (i=n;i>=1;i--)
    {
        if (ctr==k)
        break;

        if (killed[i])
        continue;

        killed[i]=true;
        ctr--;
    }

    for (i=1;i<=n;i++)
    {
        if (!killed[i])
        {
            printf("%c",str[i]);
        }
    }
    printf("\n");

    return 0;
}