using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var dictionary = new Dictionary<int, bool>

        {

            { 1, false },

            { 2, false },

            { 3, false },

            { 4, false }

        };

​

        var lowestKey = dictionary

            .Where(kv => kv.Value)

            .Select(kv => kv.Key)

            .DefaultIfEmpty(-1) // Use -1 or any default value if no true values are found

            .Min();

        if (dictionary.Any(kv => kv.Value == true))

        {

            Console.WriteLine("The ls:" + lowestKey.ToString());

        }

        Console.WriteLine("The lowest key with value true is:" + lowestKey.ToString());

    }

}