using System;
using System.Text.RegularExpressions;

public class Test
{
	public static bool DoTest(string sProp)
	{
		Regex re = new Regex(@"~\([A-Z0-1]\)|[&|>=]\([A-Z0-1],[A-Z0-1]\)");
		
		while(re.Match(sProp).Success)
		{
			sProp = re.Replace(sProp, "1");
		}
		return sProp=="1";
	}

	public static void Main()
	{
		string[] saPropositions = {
			"&(&(=(A,B),>(&(A,B),~(C))),>(A,~(&(A,B))))",
			"=(~(A),>(>(B,C),~(A)))",
			"(~(A))",
			">(A,B"
			};
		
		
		for( int idx = 0; idx<saPropositions.Length; idx++)
		{
			
			Console.WriteLine("Testing the proposition " + saPropositions[idx] + ".");
			Console.WriteLine(DoTest(saPropositions[idx]) ? "The proposition is valid" 
			: "Invalid proposition");
			
		}
	}
}