/*
   1025 Democracy in danger.
*/
#include <stdio.h>
int i,n,tot,v[101];

int partation(int arr[], int low, int high)
{
  int pivotkey=arr[low];
  while (low<high)
  {
    while ((low<high) && (arr[high]>=pivotkey)) high--;
    arr[low]=arr[high];
    while ((low<high) && (arr[low]<=pivotkey)) low++;
    arr[high--]=arr[low];
  }
  arr[low]=pivotkey;
  return low;
}

int select(int arr[], int low, int high, int Nth)
{
  int pivotloc;
  pivotloc=partation(arr, low, high)+1;
  if (low==high) return arr[low];
  if (Nth<=pivotloc)
    return select(arr, low, pivotloc-1, Nth);
  else
    return select(arr, pivotloc, high, Nth-pivotloc);
}

int main()
{
  scanf("%d",&n);
  for (i=0; i<n; i++)
    scanf("%d",&v[i]);
  for (i=1; i<=n/2+1; i++)
    tot+=(select(v, 0, n-1, i)+1)/2;
  printf("%d\n",tot);
  return 0;
}