using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

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

        {

            new Dictionary<string, string>

            {

                { "A", "a" },

                { "B", "b" }

            },

            new Dictionary<string, string>

            {

                { "C", "c" },

                { "D", "d" }

            },new Dictionary<string, string>

            {

                { "E", "e" },

                { "F", "f" }

            },

            new Dictionary<string, string>

            {

                { "A", "a" },

                { "B", "b" }

            },

            new Dictionary<string, string>

            {

                { "C", "c" },

                { "D", "d" }

            },new Dictionary<string, string>

            {

                { "E", "e" },

                { "F", "f" }

            }

        };

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

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

        {

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

        }

    }

}