using System;

public class Test
{
	public static void Main()
	{
		string stringNumber = "42";
		int number = StringToInteger(stringNumber);
		
		System.Console.WriteLine(number);
	}
	
	public static int StringToInteger(string value)
    {
        int number = 0;
        foreach (var character in value)
            number = (number << 1) + (number << 3) + (character - '0');

        return number;
    }
}