using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<Dictionary<string, long>> dictionaries = new()

        {

            new Dictionary<string, long>

            {

                { "A", 1 },

                { "B", 2 }

            },

            new Dictionary<string, long>

            {

                { "C", 3 },

                { "D", 4 }

            },new Dictionary<string, long>

            {

                { "E", 5 },

                { "F", 6 }

            },

            new Dictionary<string, long>

            {

                { "A", 1 },

                { "B", 2 }

            },

            new Dictionary<string, long>

            {

                { "C", 3 },

                { "D", 4 }

            },new Dictionary<string, long>

            {

                { "E", 5 },

                { "F", 6 }

            }

        };

        Dictionary<string, long> result = dictionaries.SelectMany(dict => dict).ToLookup(pair => pair.Key, pair => pair.Value).ToDictionary(group => group.Key, group => group.Sum());

        foreach(KeyValuePair<string, long> pair in result)

        {

            Console.WriteLine($"{pair.Key}:{pair.Value}");

        }

    }

}