1d array marks

#include<iostream>
using namespace std;

int main()
{
    double a[3];
    int array_size = 3;
    for(int i=0; i<array_size; i++)
    {
        cin>>a[i];
    }
    for(int i=0; i<array_size; i++)
    {
        cout<<"roll: " <<(i+1) << " marks: "<<a[i]<<endl;

    }
    /*for(int i=1;i<=3;i++) {
        cout<<"roll " <<(i) << " marks "<<a[i-1]<<endl;
    }*/

    double sum = 0;
    for(int i=0; i<array_size; i++)
    {
        sum = sum + a[i];
    }
    cout<< "avg marks: "<<sum/array_size <<endl;

    double highest = a[0];
    for(int i=0; i<array_size; i++) {
        if(a[i]>highest) {
            highest = a[i];
        }
    }
    cout<<"highest marks: "<<highest<<endl;

    double lowest = a[0];
    for(int i=0; i<array_size; i++) {
        if(a[i]<lowest) {
            lowest = a[i];
        }
    }
    cout<<"lowest marks: "<<lowest<<endl;



    int roll_to_be_deleted;
    cin>>roll_to_be_deleted;

    array_size = array_size-1;
    for(int i=roll_to_be_deleted; i<array_size; i++) {
        a[i] = a[i+1];
    }
}