#include<iostream>
#include<fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int m,n,a[1030],b[1030],c[1030][1030];
char d[1030][1030];
int x[1030];


int main()
{   int k,i,j;
          fin>>m>>n;
    for(i=1;i<=m;i++) fin>>a[i];
    for(i=1;i<=n;i++) fin>>b[i];

for(i=1;i<=m;i++)
    for( j=1;j<=n;j++) {if(a[i]==b[j]) { c[i][j]=1+c[i-1][j-1]; d[i][j]='\\';}
                       else {if (c[i-1][j]>c[i][j-1]) { c[i][j]=c[i-1][j]; d[i][j]='|';}
                             else {c[i][j]=c[i][j-1]; d[i][j]='-';}
                            }
                       }
fout<<c[m][n]<<endl;
i=m;
j=n;
k=0;
while(i>0 && j>0)
            { if( a[i]==b[j]) {k++;
                               x[k]=a[i];}
              if( d[i][j]=='\\') {i--;
                                 j--;}
              else if (d[i][j]=='-') j--;
              else i--;

            }
for(i=k;i>=1;i--) fout<<x[i]<<" ";

fout.close();
fin.close();
return 0;

}