#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, k;
  cin >> n >> k;
  string num;
  cin >> num;
  int master = 0;
  if (n == 1 && k > 0) {
    cout << 0;
    return 0;
  }
  for (int i = 0; i < k && master < n; i++) {
    if (master == 0) {
      cout << 1;
      if (num[0] == '1') i--;
    } else {
      cout << 0;
      if (num[master] == '0') i--;
    }
    master++;
  }
  for (int i = master; i < n; i++) {
    cout << num[i];
  }
}
