//Code by Patcas Csaba

#include <vector>
#include <string> 
#include <set> 
#include <map> 
#include <queue> 
#include <bitset> 
#include <stack>
#include <list>

#include <numeric> 
#include <algorithm> 

#include <cstdio>
#include <fstream>
#include <iostream> 
#include <sstream> 
#include <iomanip>

#include <cctype>
#include <cmath> 
#include <ctime>
#include <cassert>

using namespace std;

#define LL long long
#define PII pair <int, int>
#define VB vector <bool>
#define VI vector <int>
#define VD vector <double>
#define VS vector <string>
#define VPII vector <pair <int, int> >
#define VVI vector < VI >
#define VVB vector < VB >

#define FORN(i, n) for(int i = 0; i < (n); ++i)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define REPEAT do{ 
#define UNTIL(x) }while(!(x)); 

#define SZ size()
#define BG begin() 
#define EN end() 
#define CL clear()
#define X first
#define Y second
#define RS resize
#define PB push_back
#define MP make_pair
#define ALL(x) x.begin(), x.end()

#define IN_FILE "a.in"
#define OUT_FILE "a.out"

FILE *stream1, *stream2;

int n, m, nrNodes, matchSize = 0;
VI a, b, paired;
map <int, int> iNode, value;
VVI g;
VB was;
bool found;

void addEdge(int node1, int node2)
{
  g[node1].PB(node2);
}

void pairUp(int node)
{
  FORN(i, g[node].SZ)
  {
    int aux = g[node][i];
    if (paired[aux] == -1)
    {
      paired[node] = aux;
      paired[aux] = node;
      found = true;
      return;
    }
  }
  was[node] = true;
  FORN(i, g[node].SZ)
  {
    int aux = g[node][i];
    if (!was[aux])
    {
      was[aux] = true;
      pairUp(paired[aux]);
      if (found)
      {
        paired[node] = aux;
        paired[aux] = node;
        return;
      }
    }
  }
}

int main()
{
	//Read data
	//freopen_s(&stream1, IN_FILE, "r", stdin);
	//freopen_s(&stream2, OUT_FILE, "w", stdout);
  cin >> n >> m;
  a.RS(n + 1);
  b.RS(m + 1);
  FOR(i, 1, n) cin >> a[i];
  FOR(i, 1, m) cin >> b[i];
	
  g.RS(n + 1);
  nrNodes = n;

	//Solve
  FOR(i, 1, n)
  {
    int aux = a[i];
    if (iNode.count(aux)) addEdge(i, iNode[aux]);
    else
    {
      ++nrNodes;
      iNode[aux] = nrNodes;
      value[nrNodes] = aux;
      addEdge(i, nrNodes);
    }
    FOR(j, 1, m)
    {
      aux = a[i] - b[j];
      if (iNode.count(aux)) addEdge(i, iNode[aux]);
      else
      {
        ++nrNodes;
        iNode[aux] = nrNodes;
        value[nrNodes] = aux;
        addEdge(i, nrNodes);
      }
    }
  }

  paired.RS(nrNodes + 1, -1);
  was.RS(nrNodes + 1);
  FOR(i, 1, n)
    if (paired[i] == -1) 
    {
      fill(ALL(was), false);
      found = false;
      pairUp(i);
      if (found) ++matchSize;
    }

	//Write data
  cout << matchSize << endl;
  FOR(i, 1, n) 
    if (paired[i] == -1) cout << a[i] << " ";
    else cout << value[paired[i]] << " ";

	return 0;
}