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