#include<stdio.h>
#define max(a,b)((a>b)?a:b)
#define N 1024
int m,n,A[N],B[N],v[N][N],sir[N],nr;
int main(void){
    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;j<=n;++j)
            if(A[i]==B[j])
				v[i][j]=1+v[i-1][j-1];
            else
				v[i][j]=max(v[i][j-1],v[i-1][j]);
		for(i=m,j=n;i;)
			if(A[i]==B[j])
				sir[++nr]=A[i],--i,--j;
			else 
				if(v[i][j-1]>v[i-1][j])   
					--j;
			else
				--i;
	printf("%d\n",nr);
	for(i=nr;i;--i)
		printf("%d ",sir[i]);
	printf("\n");
	fclose(stdin);
	fclose(stdout);
	return 0;
}