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