#include <stdio.h>

int med3(int a, int b, int c);
void quicksort(int left, int right, int a[]);

int main(void){
  int i, l, r, N, A[1050];
  
  scanf("%d", &N);
  for(i=0;i<N;i++) scanf("%d", &A[i]);

  quicksort(0, N-1, A);

  printf("%f\n", (A[(N-1)/2]+A[N/2])/2.0);
  
  return 0;
}

void swap(int i, int j, int a[]){
  int temp;
  temp=a[i];
  a[i]=a[j];
  a[j]=temp;
}

int med3(int a, int b, int c){
  if(a<=b){
    if(b<=c) return b;		/* a<b<c */
    else if(c<=a) return a;	/* c<a<b */
    else return c;		/* a<c<b */
  }
  /* a>b */
  else if(c>=a) return a;	/* c>a>b */
  else if(b>=c) return b;	/* a>b>c */
  else return c;		/* a>c>b */
}

void quicksort(int left, int right, int a[]){
  int i, j, pivot;
  if(right-left>1){
    pivot=med3(a[left], a[right], a[left+1]);
    i=left;
    j=right;
    while(1){
      while(a[i]<pivot) i++;
      while(a[j]>pivot) j--;
      if(i<j){
	swap(i, j, a);
	i++;
	j--;
      }
      else break;
    }
    quicksort(left, i-1, a);
    quicksort(i, right, a);
  }
  else if(right-left)
    if(a[left]>a[right]) swap(left, right, a);
}