C++ :

#include<stdio.h>
int main()
{
    int n,m,ans;
    while(scanf("%d",&n)!=EOF)
    {ans=0;
        for(int i=0;i<n;i++)
        {
            scanf("%d",&m);
            ans+=m;
        }
        printf("%d",ans/2);
        if(ans%2)
            printf(".5");
        printf("\n");
    }
    return 0;
}

Python :

while True:
    raw_input()
    a=[]
    sum = 0
    for n in raw_input().split():
        a.append(int(n))
    for i in range(len(a)):
        sum+=a[i]*5
    if sum % 10:
        print sum/10.0
    else:
         print sum/10