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