using System;

using System.Collections.Concurrent;

public class Program

{ 

    protected ConcurrentDictionary<string, int> Dict { get; set; } = new ConcurrentDictionary<string, int>();

    public static void Main()

    {

        bool varialbe = false;

        Console.WriteLine($"Hello World: {varialbe}");

    }

    public int? GetProjectId(string projectNumber)

    {

        Dict.TryGetValue(projectNumber, out var projectId);

        return projectId;

    }

}