using System;
using System.Collections.Generic;
using System.Linq;

namespace Socks
{
    class Program
    {
        static void Main(string[] args)
        {
            var leftSocks = Console.ReadLine()
                .Split()
                .Select(int.Parse)
                .ToArray();

            var rightSocks = Console.ReadLine()
                .Split()
                .Select(int.Parse)
                .ToArray();

            Stack<int> left = new Stack<int>(leftSocks);
            Queue<int> right = new Queue<int>(rightSocks);
            List<int> pairs = new List<int>();

            int pairOfSocks;

            while (left.Count > 0 && right.Count > 0)
            {
                int leftSock = left.Peek();
                int rightSock = right.Peek();

                if (leftSock > rightSock)
                {
                    pairOfSocks = rightSock + leftSock;
                    pairs.Add(pairOfSocks);
                    left.Pop();
                    right.Dequeue();

                    if (left.Count > 0 && right.Count > 0)
                    {
                        leftSock = left.Peek();
                        rightSock = right.Peek();
                    }

                }

                if (rightSock > leftSock)
                {
                    left.Pop();

                    if (left.Count > 0)
                    {
                        leftSock = left.Peek();
                    }

                }

                if (leftSock == rightSock)
                {

                    rightSock++;
                    left.Pop();
                    left.Push(rightSock);
                    right.Dequeue();

                    if (right.Count > 0)
                    {
                        rightSock = right.Peek();
                    }
                }
            }

            int biggestSet = pairs.OrderByDescending(p => p).FirstOrDefault();

            Console.WriteLine(biggestSet);
            Console.WriteLine(string.Join(" ", pairs));
        }
    }
}