#include <bits/stdc++.h>
using namespace std;
int n, m, j, ans;
string a, b, c;
int s[255];
int main() {
  cin >> n >> m;
  cin >> a;
  if (n == m) {
    return 0;
  }
  for (int i = 0; i < n; i++) {
    b += a[i];
  }
  sort(b.begin(), b.end());
  for (int i = m; i < n; i++) {
    s[int(b[i])]++;
  }
  for (int i = n - 1; i >= 0; i--) {
    if (s[int(a[i])] != 0) {
      c += a[i];
      s[int(a[i])]--;
    }
  }
  for (int i = c.size() - 1; i >= 0; i--) {
    cout << c[i];
  }
  return 0;
}
