#include <stdio.h>

int main(void){
  int n,a[1001],z;
  float center;
  scanf("%d",&n);
  for(int i = 0; i < n; i++){
    scanf("%d",&a[i]);
  }

  for(int i = 0; i < n; i++){
    int min = 10000,minpoint = 0;
    for(int j = i; j < n; j++){
      if(min > a[j]){
        min = a[j];
        minpoint = j;
      }
    }
    z = a[i];
    a[i] = a[minpoint];
    a[minpoint] = z;
  }
  if(n % 2 == 1)center = (float)a[n / 2];
  else center = ((float)a[n / 2] + a[n / 2 - 1]) / 2;
  printf("%f\n",center);
}