special.cs

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

namespace Special
{
    class Program
    {
        static void Main(string[] args)
        {
            int counter = 0;
    	    int result = 0;
    	    int tmp; // tmp used for input

    	    List<int> numbers = new List<int>();
    	
    	    while (counter < 25)
    	    {
    		Console.Write("Enter a Number : ");
                string input = Console.ReadLine();

                if (!string.IsNullOrEmpty(input))
                {
                    // ofcourse if not tmp isString
                    tmp = int.Parse(input);
                    
                    if (tmp >= 0)
                    {
                        if (IsOdd(tmp))
                        {
                            // only odd numbers added into list
                            numbers.Add(tmp);
                        }
                        counter += 1;
                    }
                    else
                    {
                        Console.Write("Please enter positive number");
                    }
                }
                else 
                {
                    Console.WriteLine("Please write some number");
                }
    	    }
        
            foreach (int i in numbers)
            {
                result += (int)Math.Pow(i, 2);       
            }
	    
	    // finally
            Console.WriteLine(result);
        }

        public static bool IsOdd(int value)
        {
	    return value % 2 != 0;
        }       
    }
}