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