输入十个数字求平均数

using System;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters;

class All
{
    class program
    {
        static void Main(string[] args)
        {
            int[] num = new int[10];
            for (int i = 0; i < 10; i++)
            {
                Console.Write("请输入第");
                Console.Write(i);
                Console.Write("个字符:");
                string str= Console.ReadLine();
                //Console.WriteLine();
                bool decision = true;
                for(int j=0;j 57)
                    {
                        decision = false;
                        break;
                    }
                }
                if (!decision)
                {
                    i--;
                    Console.WriteLine("请输入数字");
                }
                else num[i] = int.Parse(str);
            }
            Console.Write("平均数是");
            Console.Write(num.Average());
        }
    }
}