#include<stdio.h>

int X,Y,sol[1200],n,m,i,x[1200],y[1200],j,a[1100][1100];

int max(int a,int b){

if(a>=b)
return a;

return b;

}


int main(){


FILE *f=fopen("cmlsc.in","r");

fscanf(f,"%d %d",&n,&m);

  for(i=1;i<=n;i++)
  fscanf(f,"%d",&x[i]);

  for(i=1;i<=m;i++)
  fscanf(f,"%d",&y[i]);


fclose(f);


for(i=1;i<=n;i++){
  for(j=1;j<=m;j++){

    if(x[i]==y[j])
    a[i][j]=a[i-1][j-1]+1;

    else
    a[i][j]=max(a[i-1][j],a[i][j-1]);

  }


}

int k=0;

X=n;
Y=m;


while(a[X][Y]!=0){

  if(x[X]==y[Y]){
  k++;
  sol[k]=x[X];
  X--;
  }

  else{

    if(a[X-1][Y]>=a[X][Y-1])
    X--;

    else
    Y--;

  }

}


FILE *g=fopen("cmlsc.out","w");
fprintf(g,"%d\n",a[n][m]);

  for(i=k;i>=1;i--)
  fprintf(g,"%d ",sol[i]);

fclose(g);

return 0;
}