static void Main(string[] args)
{
var groupingcheck = new GroupingCheck();
Console.WriteLine("Please enter an expression.");
string infix = Console.ReadLine();
if (!groupingcheck.IsValidGrouping(infix))
{
Console.WriteLine("Brackets for grouping are incorrect. Please enter a valid expression.");
Console.ReadLine();
Console.Clear();
Console.WriteLine("Please enter an expression.");
infix = Console.ReadLine();
}
var InfixToPostfixConverter = new InfixToPostfixConverter(infix);
Console.WriteLine(InfixToPostfixConverter.Output);
Console.ReadLine();
}