Average char delimiter

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
//You will receive an array of strings as input. Your task is to find the average character within every string in the array. As in, //take every character’s ASCII code, sum it and divide the result by the sum of the count of all the letters in the array.
//Example:
//a b ab abc abc  a, b, a, b a, b, c, a, b, c  sum: 978  Divide it by 10: 97.8  97
//After you find the average sum, convert it to its ASCII character representation, convert it to uppercase and print the original //array, delimited by that character.

namespace char_delimiter
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] arr = Console.ReadLine().Split(' ').ToArray();
            int sumAllElements = 0;
            int countAllElements = 0;
            var delimiter = string.Empty;

            for (int i = 0; i < arr.Length; i++)
            {
                string currentElement = arr[i];
                for (int j = 0; j < currentElement.Length; j++)
                {
                    int letter = currentElement[j];
                    countAllElements ++;
                    sumAllElements += letter;
                }
            }
            int avgSum = sumAllElements / countAllElements;
            if (avgSum >= 97 && avgSum <= 122)
            {
                avgSum -= 32;
            }
            char avgChar = (char)avgSum;
            delimiter += avgChar;
            Console.WriteLine(string.Join(delimiter, arr));
        }
    }
}