#include<fstream.h>     
int i,j,n,m,s,sl[1025],a[1025],b[1025],v[1025][1025];     
ifstream fin("cmlsc.in");     
ofstream fout("cmlsc.out");     
void citire(){     
fin>>n>>m;     
for(i=1;i<=n;i++)     
fin>>a[i];     
for(i=1;i<=m;i++)     
fin>>b[i];     
}     
int max(int a,int b){     
return (a>b)?a:b;     
}     
void din(){     
for(i=1;i<=n;i++)     
for(j=1;j<=m;j++)     
if(a[i]==b[j])     
v[i][j]=1+v[i-1][j-1];     
else     
v[i][j]=max(v[i-1][j],v[i][j-1]);     
i=n;     
j=m;     
while(i>0&&j>0)     
if(a[i]==b[j]){     
sl[++s]=a[i];     
i--;     
j--;     
}     
else     
if(v[i-1][j]>v[i][j-1])     
i--;     
else     
j--;     
fout<<v[n][m]<<'\n';     
for(i=s;i>=1;i--)     
fout<<sl[i]<<" ";     
}     
int main(){     
citire();     
din();     
return 0;        
}