Задача: 2-4-8

Решение

using System;

namespace _2_4_8 {
  class Program {
    static void Main() {
      decimal a = decimal.Parse(Console.ReadLine());
      decimal b = decimal.Parse(Console.ReadLine());
      decimal c = decimal.Parse(Console.ReadLine());

      decimal r = 0;
      switch ((int) b) {
      case 2:
        r = a % c;
        break;
      case 4:
        r = a + c;
        break;
      case 8:
        r = a * c;
        break;
      }

      int remainder = r % 4;
      if (remainder == 0) {
        Console.WriteLine(r / 4);
      } else {
        Console.WriteLine(remainder);
      }
      Console.WriteLine(r);
    }
  }
}