C#数值字符串转化为数值

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = Console.ReadLine();
            Console.WriteLine(str+1);
            int a = Convert.ToInt32(str);
            Console.WriteLine(a+1);
        }
    }
}