using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Dictionary<string,Dictionary<string,string>> myDict = new Dictionary<string,Dictionary<string,string>>();

        myDict.Add("FaceMasks",new Dictionary<string, string>{{"127191_ItemCode","127191"},

                                                              {"251719_ItemCode","251719"},

                                                              {"81910_ItemCode","81910"},

                                                              {"121211_ItemCode","121211"}});

        string match = "121211";

        Dictionary<string,string> typeDictionary = new Dictionary<string,string>();

        typeDictionary.Add("ABC_127191","127191");

        typeDictionary.Add("ABC_251719","251719");

        typeDictionary.Add("ABC_81910","81910");

        typeDictionary.Add("ABC_121211","121211");

            typeDictionary.Add("XYZ_121211","121211");

        if(typeDictionary.ContainsValue(match))

        {

            foreach(var t in typeDictionary.Where(a=> a.Value== match))

            {

                Console.WriteLine(t.Key,t.Value);

            }

        }

​

    }

}