#include <bits/stdc++.h>
using namespace std;
int n, k;
const int maxn = 5 * 1e5;
string s;
struct node {
  int num;
  int pos;
};
node a[maxn];
bool cmp(node a, node b) {
  if (a.num == b.num)
    return a.pos < b.pos;
  else
    return a.num < b.num;
}
int main() {
  cin >> n >> k;
  cin >> s;
  int len = s.size();
  for (int i = 0; i < len; i++) {
    a[i].num = s[i] - 'a' + 1;
    a[i].pos = i;
  }
  a[len].num = a[len].pos = 0x3f3f3f3f;
  sort(a, a + len, cmp);
  int t = a[k].num;
  int st = a[k].pos;
  for (int i = 0; i < len; i++) {
    int p = s[i] - 'a' + 1;
    if (p > t) cout << s[i];
    if (p == t && i >= st) cout << s[i];
  }
  cout << endl;
  return 0;
}
