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

namespace ConsoleApp11
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Random random = new Random();
            int sum = 0;
            int multiplicityThree = 3;
            int multiplicityFive = 5;
            int maximumRandomNumber = 100;
            int number = random.Next(maximumRandomNumber);

            for (int i = 0; i <= number; i++)
            {
                if(i % multiplicityThree == 0 || i % multiplicityFive == 0)
                {
                    sum +=i;
                }
            }

            Console.WriteLine($"Сумма положительных чисел кратных {multiplicityThree} и {multiplicityFive} меньше {number} будет {sum}");
        }
    }
}