#include <cstdio>
#define nmax 1024
//#define for(i, a, b) for (i = a; i <= b; ++i)
#define maxim(a, b) ((a > b) ? a : b)
using namespace std;
int m, n, a[nmax], b[nmax], d[nmax][nmax], sir[nmax], bst;
int main(){
int i,j;
freopen("cmlsc.in","r",stdin);
freopen("cmlsc.out","w",stdout);
scanf("%d %d", &m, &n);
for (i=1;i<=m;++i) scanf("%d", &a[i]);
for (i=1;i<=n;++i) scanf("%d", &b[i]);
for (i=1;i<=m;++i)
for (j=1;i<=n;++i)
if ( a[i] == b[j] ) d[i][j] = 1 + d[i-1][j-1];
else d[i][j] = maxim( d[i-1][j], d[i][j-1] );
for (i = m, j = n; i; )
if ( a[i] == b[j] ) sir[++bst] = a[i], --i, --j;
else if ( d[i-1][j] < d[i][j-1] ) --j;
else --i;
printf("%d\n", bst);
for (i = bst; i; --i) printf("%d ", sir[i]);
return 0;
}
/*
#include <stdio.h>
#define maxim(a, b) ((a > b) ? a : b)
#define FOR(i, a, b) for (i = a; i <= b; ++i)
#define NMax 1024
int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;
int main(void)
{
int i, j;
freopen("cmlsc.in", "r", stdin);
freopen("cmlsc.out", "w", stdout);
scanf("%d %d", &M, &N);
FOR (i, 1, M)
scanf("%d", &A[i]);
FOR (i, 1, N)
scanf("%d", &B[i]);
FOR (i, 1, M)
FOR (j, 1, N)
if (A[i] == B[j])
D[i][j] = 1 + D[i-1][j-1];
else
D[i][j] = maxim(D[i-1][j], D[i][j-1]);
for (i = M, j = N; i; )
if (A[i] == B[j])
sir[++bst] = A[i], --i, --j;
else if (D[i-1][j] < D[i][j-1])
--j;
else
--i;
printf("%d\n", bst);
for (i = bst; i; --i)
printf("%d ", sir[i]);
return 0;
}
*/