using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var names = new []{"A","B","A","B","C"};

        var numbers = new []{1,2,3,4,5};

        var combined = names.Zip(numbers, (name,number) => new{ Name = name, Number = number});

        var result = combined.GroupBy(x => x.Name).Select(g => new {Name=g.Key, Value = g.Sum(x => x.Number)});

        foreach(var item in result)

        {

            Console.WriteLine($"{item.Name}: {item.Value}");

        }

    }

}