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