#include <stdio.h>
#include <stdlib.h>

int cmp(const void *a,const void *b)
{
	return *(int *)a-*(int *)b;
}

int main()
{
    int num[250001];
    int n,i,m;
    double ans;
    scanf("%d",&n);
    for(i=0;i<n;i++) scanf("%d",num+i);
    qsort(num,n,sizeof(int),cmp);
    m=n/2;
    printf("%.1lf",n%2?num[m]:num[m]/2.0+num[m-1]/2.0);    

}