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