#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  int64_t N, n, k, i = 1;
  cin >> n >> k;
  cin >> s;
  N = s.size();
  if (N == 1 && k != 0) {
    cout << "0" << endl;
  } else if (N == 1 && k == 0) {
    cout << s << endl;
  } else {
    if (s[0] != '1' && k != 0) {
      s[0] = '1';
      k--;
    }
    while (k--) {
      if (i == n) {
        break;
      } else {
        if (s[i] != '0') {
          s[i] = '0';
        } else {
          k++;
        }
      }
      i++;
    }
    cout << s << endl;
  }
  return 0;
}
