#include <stdio.h>
#include <stdlib.h>

#define MAX_N 1025
#define FIN "cmlsc.in"
#define FOUT "cmlsc.out"

int A[MAX_N];
int B[MAX_N];

short O[MAX_N][MAX_N];
int S[MAX_N];
int N, M, i;
int L;
int cnt;

	inline int MAX (int a, int b)
	{
		if (a > b) return a; else return b;
	}

	void build (int n, int m, int l)
	{
       int i, j;  
	   for (i = n, j = m; i && j; )  
         if (A[i] == B[j])  
            S[++cnt] = A[i], --i, --j;  
            else 
                 if (O[i][j-1] < O[i-1][j])  
                    --i;  
                 else  
                    --j;  
  
    printf("%d\n", L);  
    for (i = cnt; i; --i)  
        printf("%d ", S[i]);  
    printf("\n");  
	}

	void solve ()
	{
		int i, j;
		for (i = 1; i <= N; ++i)
		    for (j = 1; j <= M; ++j)
			if (A[i] == B[j])
				O[i][j] = O[i - 1][j - 1] + 1;
			else O[i][j] = MAX (O[i - 1][j], O[i][j - 1]);
		L = O[N][M];
		build (N, M, L);
	}

	int main ()
	{
		freopen (FIN, "r", stdin);
		freopen (FOUT, "w", stdout);

		scanf ("%d %d", &N, &M);
		for (i = 1; i <= N; ++i) scanf ("%d", A + i);
		for (i = 1; i <= M; ++i) scanf ("%d", B + i);

		solve ();
                return 0;
	}