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