#include <cstdio>
#define nmax 1025
#define max(a,b) (a)>(b)?(a):(b)

int n,m,x[nmax],y[nmax],sol[nmax][nmax];

void smax()
{   int i,j;
    for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)if(x[i]==y[j])sol[i][j]=1+sol[i-1][j-1];else
    sol[i][j]=max(sol[i-1][j],sol[i][j-1]);
}

void printsol(int i,int j)
{   if(x[i]==y[j]){printsol(i-1,j-1);printf("%d ",x[i]);} else
    {   if(sol[i][j]=sol[i-1][j]) printsol(i-1,j);else
        if(sol[i][j]=sol[i][j-1]) printsol(i,j-1); }
}

int main()
{   int i;
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(i=1;i<=n;i++)scanf("%d",&x[i]);
    for(i=1;i<=m;i++)scanf("%d",&y[i]);
    smax();
    printf("%d\n",sol[n][m]);
    printsol(n,m);
}