#include <stdio.h>

int len[1030][1030],drum_rec[1030],k,x[1030],y[1030];

int main(){
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    int n,m,i,j;
    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]);
    
    for (i=1;i<=n;i++)    
        for (j=1;j<=m;j++)
            if (x[i]==y[j]) len[i][j]=len[i-1][j-1]+1;
            else {if (len[i][j-1]>len[i-1][j]) len[i][j]=len[i][j-1];
                  else len[i][j]=len[i-1][j];
                 } 
    
    i=n,j=m;
    while (i!=0 && j!=0){
          if (x[i]==y[j]) drum_rec[k++]=x[i],i--,j--;
          else {             
          if (len[i-1][j]==len[i][j]) i--;
          else if (len[i][j-1]==len[i][j]) j--;
          }
          }
          
    printf("%d\n",len[n][m]);                
    for(i=k-1;i>=0;i--) printf("%d ",drum_rec[i]);
    
    return 0;
    }