9.1.ProblemsForChampions-PartI-CrossingSequences_AngelKalink

using System;

class CrossingSequences
{
    static void Main(string[] args)
    {
        int tribonacci1 = int.Parse(Console.ReadLine());
        int tribonacci2 = int.Parse(Console.ReadLine());
        int tribonacci3 = int.Parse(Console.ReadLine());
        int spiralStart = int.Parse(Console.ReadLine());
        int spiralStep = int.Parse(Console.ReadLine());

        int spiralStep1 = 0;
        int spiralStep2 = 0;
        int number = spiralStep;
        int count = 0;

        if (tribonacci1 == spiralStart || tribonacci2 == spiralStart
                || tribonacci3 == spiralStart)
        {
            Console.WriteLine(spiralStart);
        }
        else
        {
            while (spiralStep1 <= 1000000)
            {
                int tribonacciNext = 0;
                int a = tribonacci1;
                int b = tribonacci2;
                int c = tribonacci3;
                while (tribonacciNext <= spiralStep2)
                {
                    tribonacciNext = a + b + c;
                    if (tribonacciNext == spiralStep1 || tribonacciNext == spiralStep2)
                    {
                        Console.WriteLine(tribonacciNext);
                        spiralStart = 1000000;
                        count++;
                        break;
                    }
                    a = b;
                    b = c;
                    c = tribonacciNext;
                }
                spiralStep1 = spiralStart + spiralStep;
                if (spiralStep1 == tribonacci1 || spiralStep1 == tribonacci2
                        || spiralStep1 == tribonacci3)
                {
                    Console.WriteLine(spiralStep1);
                    break;
                }
                spiralStep2 = spiralStep1 + spiralStep;
                if (spiralStep2 == tribonacci1 || spiralStep2 == tribonacci2
                        || spiralStep2 == tribonacci3)
                {
                    Console.WriteLine(spiralStep2);
                    break;
                }
                spiralStart = spiralStep2;
                spiralStep += number;
            }
        }
        if (spiralStep1 > 1000000 && count == 0)
        {
            Console.WriteLine("No");
        }
    }
}