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