Arrays -- how to use them

using System;
using System.Linq;

namespace xx.TEST
{
    class Test
    {
        static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            int[] arr = new int[n];
            for (int i = 0; i < n; i++)
            {
                arr[i] = int.Parse(Console.ReadLine());
            }
            int sum = 0;
            int min = int.MaxValue;
            int max = int.MinValue;

            for (int i = 0; i < n; i++)
            {
                sum = sum + arr[i];
                if (arr[i]<min)
                {
                    min = arr[i];
                }
                max = Math.Max(max, arr[i]);

            }
            //Console.WriteLine($"Sum = {sum}");
            //Console.WriteLine($"Min = {min}");
            //Console.WriteLine($"Max = {max}");
            //Console.WriteLine($"First = {(arr[0])}");
            //Console.WriteLine($"Last = {(arr[arr.Length-1])}");
            //Console.WriteLine($"Average = {(double)(sum/n)}");

            Console.WriteLine($"Sum = {(arr.Sum())}");
            Console.WriteLine($"Min = {(arr.Min())}");
            Console.WriteLine($"Max = {(arr.Max())}");
            Console.WriteLine($"First = {(arr.First())}");
            Console.WriteLine($"Last = {(arr.Last())}");
            Console.WriteLine($"Average = {(arr.Average())}");
        }
    }
}