using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        int[] array = new int[]{3, 2, -2, 5, -3, 5,-5};

        int result = 0; 

        Dictionary<int, int> d = new Dictionary<int,int>();

        foreach(int item in array)

        {

            if( d.ContainsKey( Math.Abs(item) ) )

               {

                   if(  Math.Abs(item) > result )

                   {

                       result = Math.Abs(item);

                   }

               }

               else

               {

                   d.Add(Math.Abs(item),Math.Abs(item));

               }

        }

        Console.WriteLine(result);

    }

}