using System;

public static class NumericParsingExtender
{
    public static Int32 ToInt32(this String input, Int32 defaultValue = 0)
    {
      if (String.IsNullOrEmpty(input)) return defaultValue;
      Int32 val;
      return Int32.TryParse(input, out val) ? val : defaultValue;
    }
}

public class PseudoControl
{
    public String Text { get; set; }
    public PseudoControl(String text)
    {
        this.Text = text;
    }
}

public class Test
{
	public static void Main()
	{
		PseudoControl txtChild1 = new PseudoControl("12");
        PseudoControl txtChild2 = new PseudoControl(null);
        PseudoControl txtChild3 = new PseudoControl(String.Empty);
        PseudoControl txtWife1 = new PseudoControl("42");
        PseudoControl txtWife2 = new PseudoControl("invalid");
        PseudoControl txtWife3 = new PseudoControl("20.13");
        
        Int32 total = txtChild1.Text.ToInt32()
            + txtChild2.Text.ToInt32()
            + txtChild3.Text.ToInt32()
            + txtWife1.Text.ToInt32()
            + txtWife2.Text.ToInt32()
            + txtWife3.Text.ToInt32();
        Console.WriteLine("Total: {0}", total);
	}
}