#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, s = 0, n;
  string st;
  cin >> n >> k;
  cin >> st;
  if (k == 0) {
    cout << st;
    return 0;
  }
  if (st[0] != '1') st[0] = '1', s++;
  for (i = 1; i < n; i++) {
    if (s == k) break;
    if (st[i] != '0') st[i] = '0', s++;
  }
  if (n == 1 and k == 1) {
    cout << 0;
    return 0;
  }
  cout << st;
}
