#include <bits/stdc++.h>
int ar[10000000];
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int n, k;
  cin >> n >> k;
  string st;
  cin >> st;
  if (k == 0)
    cout << st << endl;
  else if (n == 1 && k >= 1)
    cout << "0" << endl;
  else {
    int count = 0;
    if (st[0] != '1') {
      st[0] = '1';
      count++;
    }
    for (int i = 1; i < n; i++) {
      if (count == k) break;
      if (st[i] != '0') {
        st[i] = '0';
        count++;
      }
    }
    cout << st << endl;
  }
  return 0;
}
