using System.Diagnostics;
static public int Reverse(int needToReverse)
Trace.Assert(needToReverse > 0);
return Reverse(0, needToReverse);
static public int Reverse(int alreadyReversed, int needToReverse)
return Reverse(10 * alreadyReversed + needToReverse % 10, needToReverse / 10);
static public void Main()
foreach(int n in new int[]{ 1, 12, 123, 2005, 333, 20, 2018})
Console.WriteLine("{0} -> {1}", n, Reverse(n));