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