#include <bits/stdc++.h>
using namespace std;
long long n, k;
void solve() {
  string a, ans;
  cin >> a;
  long long i, j, l = a.length(), b[26];
  for (i = 0; i < 26; i++) b[i] = 0;
  for (i = 0; i < l; i++) b[a[i] - 'a']++;
  for (i = 0; i < 26; i++) {
    if (k <= 0) break;
    if (k >= b[i]) {
      k -= b[i];
      b[i] = 0;
    } else {
      b[i] -= k;
      break;
    }
  }
  for (i = l - 1; i >= 0; i--)
    if (b[a[i] - 'a']) {
      ans.push_back(a[i]);
      b[a[i] - 'a']--;
    }
  l = ans.length();
  for (i = 0; i < l / 2; i++) {
    char ch = ans[i];
    ans[i] = ans[l - 1 - i];
    ans[l - 1 - i] = ch;
  }
  cout << ans << endl;
}
int main() {
  while (cin >> n >> k) solve();
}
