using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("How many numbers : ");

        int n = int.Parse(Console.ReadLine());

        int sum = 0; 

        for(int i = 0; i < n; i++)

        {

            int number = int.Parse(Console.ReadLine());

            if (number <= 0)

            {

                Console.WriteLine("Invalid number! Must be positive.");

                return;

            }

            sum += number;

        }

​

        Console.WriteLine("Read " + n + " numbers.");

        Console.WriteLine("Their sum is : " + sum);

    }

}

​

​

​

​