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