MakeItAnagram - using one array, first string each char - add to the array, second string each char - take away from the array, sum of abs value of each item.

MakeItAnagram5.cs

using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    static void Main(String[] args)
    {
        string A = Console.ReadLine();
        string B = Console.ReadLine();
        int[] a = new int[123];
        int length = A.Length;
        for (int i = 0; i < length; i++)
        {
            a[A[i]]++;
        }
        length = B.Length;
        for (int i = 0; i < length; i++)
        {
            a[B[i]]--;
        }
        int count = 0;
        for (int i = 0; i < 123; i++)
        {
            int k = a[i];
            if (k != 0)
            {
                count += k < 0 ? -k : k;
            }
        }
        Console.WriteLine(count);
    }
}