#include "stdafx.h"
#include <iostream>
using namespace std;
const int size=20;
void read_a(double a[], int &n){
cout<<"Enter the number of elements: "; cin>>n; if(n>size)n=size;
for(int i=0;i=0;i<n;i++)cout<<"Enter a [ "<<i+1<<" ]= ", cin>>a[i];}
double sr_ar_nech_cifr(double a[], int n)
{double b=0; for(int i=0;i<n;i+=2)b+=a[i]; return b/((n+1)/2);}
void write_m(double a[], int n){
double s=sr_ar_nech_cifr(a, n);
cout<<"Sum = "<<(n+1)/2*s<<"\nSrednee arifm = "<<s<<endl;}
int main(){
double a[size]; int n; read_a(a,n); write_m(a,n);
cout<<"Press Enter for exit\n"; cin.get(); cin.get();}