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