Magic Dates

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

namespace Magic_Dates
{
    class Program
    {
        static void Main(string[] args)
        {
            var count = 0;
            var lastDay = 0;
            int y = 0;
            int y1 = 0; int y2 = 0; int y3 = 0; int y4 = 0; int y5 = 0; int y6 = 0; int y7 = 0;
            var x1 = 0; var x2 = 0; var x3 = 0; var x4 = 0; var x5 = 0; var x6 = 0; var x7 = 0; var x8 = 0;

            int year1 = int.Parse(Console.ReadLine());
            int year2 = int.Parse(Console.ReadLine());
            int num = int.Parse(Console.ReadLine());

            for (int year = year1; year <= year2; year++)
            {
                for (int month = 1; month <= 12; month++)
                {
                    if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12)
                    {
                        lastDay = 31;
                    }
                    else if (month == 4 || month == 6 || month == 9 || month == 11)
                    {
                        lastDay = 30;
                    }
                    else if (month == 2)
                    {
                        lastDay = 28;
                        if (year % 4 == 0)
                        {
                            lastDay = 29;
                            if (year % 100 == 0)
                            {
                                lastDay = 28;
                                if (year % 400 == 0)
                                {
                                    lastDay = 29;
                                }
                            }
                        }
                    }
                    for (int date = 1; date <= lastDay; date++)
                    {
                        x1 = date / 10;
                        x2 = date % 10;
                        x3 = month / 10;
                        x4 = month % 10;
                        x5 = year / 1000;
                        x6 = (year / 100) % 10;
                        x7 = (year / 10) % 10;
                        x8 = year % 10;

                        y1 = x1 * x2 + x1 * x3 + x1 * x4 + x1 * x5 + x1 * x6 + x1 * x7 + x1 * x8;
                        y2 = x2 * x3 + x2 * x4 + x2 * x5 + x2 * x6 + x2 * x7 + x2 * x8;
                        y3 = x3 * x4 + x3 * x5 + x3 * x6 + x3 * x7 + x3 * x8;
                        y4 = x4 * x5 + x4 * x6 + x4 * x7 + x4 * x8;
                        y5 = x5 * x6 + x5 * x7 + x5 * x8;
                        y6 = x6 * x7 + x6 * x8;
                        y7 = x7 * x8;
                        y = y1 + y2 + y3 + y4 + y5 + y6 + y7;

                        if (y == num)
                        {
                            Console.WriteLine($"{x1}{x2}-{x3}{x4}-{x5}{x6}{x7}{x8}");
                            count++;
                        }
                    }
                }
            }
            if (count == 0)
            {
                Console.WriteLine("No");
            }
        }
    }
}