using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        int i = 234;

        int j = -123;

        Console.WriteLine(reverse(i));

        Console.WriteLine(reverse(j));

    }

​

    static int reverse(int i)

    {

        int sign = i / Math.Abs(i);

        var abs = string.Concat(Math.Abs(i).ToString().Reverse());

        return int.Parse(abs) * sign;

    }

}