using System;

namespace CSharpExercises
{
    class BitsToNumberTask
    {
        static int BitsToNumber(string bits)
        {
            var number = 0;

            for (var i = 0; i < bits.Length; i++)
            {
                number += (int)(char.GetNumericValue(bits[i]) * Math.Pow(2, bits.Length - i - 1));
            }

            return number;
        }

        static void Main(string[] args)
        {
            Console.WriteLine(BitsToNumber("0"));                   // 0
            Console.WriteLine(BitsToNumber("00001011000001"));      // 705
            Console.WriteLine(BitsToNumber("10001110001010100"));   // 72288
        }
    }
}