ЕЙ ГО ВЕ

using System;
using System.Linq;

namespace MostFrequentNumbers
{
	class Program
	{
		public static void Main(string[] args)
		{
			int[] array = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

			int start = 0;
			int end = 0;
			int bestStart = 0;
			int bestLenght = 0;
			int totalLenght = 0;

			int currentNumber = 0;
			int counter = 0;
			int bestCounter = 0;
			int leftMostPosition = 0;
			for (int currentElement = 0; currentElement < array.Length; currentElement++)
			{
				currentNumber = array[currentElement];

				for (int currentCheck = 0; currentCheck < array.Length; currentCheck++)
				{
					if (currentNumber == array[currentCheck])
					{
						counter++;
					}
				}

				if (counter > bestCounter)
				{
					bestCounter = counter;
					leftMostPosition = currentElement;
				}
				counter = 0;
			}

			Console.WriteLine(array[leftMostPosition]);

		}
	}
}