//Ненавижу 1С для mista.ru
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp7
{
    class Program
    {
        static void Main(string[] args)
        {
            var result = 0;
            var s = Console.ReadLine();
            var builds = s.Split(' ').Select(c => Int32.Parse(c)).ToList();
            int last = builds.Count()-1;
            int based = 0;            
            while(based!=last)
            {
                var nextBased = based;
                var maxIndex = based+1;                
                for (int i=based+1;i<=last;i++)
                {
                    if(builds[i]>builds[based])
                    {                        
                        nextBased = i;
                        break;
                    }
                    else if(builds[i]>=builds[maxIndex])
                    {
                        maxIndex = i;
                    }
                }
                if(nextBased==based)
                {
                    nextBased = maxIndex;
                }
                var level = Math.Min(builds[based], builds[nextBased]);
                for(int i=based+1;i<nextBased;i++)
                {
                    result += (level - builds[i]);
                }
                based = nextBased;
            }
            Console.WriteLine(result);            
            Console.ReadKey();
        }
    }
}