C#倒序输出字符

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace retrun
{
class Program
{
static void Main(string[] args)
{
string act = Console.ReadLine();
string rev = "";
for (int index = act.Length-1;index >= 0;index--)
{
rev += act[index];
}
Console.WriteLine("{0}",rev);
Console.ReadKey();
}
}
}