using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var planets = new Dictionary<int, string>()

        {

            [1] = "Mercury",

            [2] = "Venus",

            [3] = "Earth"

        };

​

        Console.WriteLine(planets.ContainsValue("Venus")); // Returns True

    }

}