#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k == 0) {
    cout << s;
  } else if (s.length() == 1)
    cout << 0;
  else {
    int k1 = 0;
    if (s[0] != '1') {
      s[0] = '1';
      k1++;
    }
    for (int i = 1; i < n; i++) {
      if (k1 == k)
        break;
      else {
        if (s[i] != '0') {
          s[i] = '0';
          k1++;
        }
      }
    }
    cout << s;
  }
}
