#include <cstdio>
#define maxn 1024

short a[maxn],b[maxn], dp[maxn][maxn],t[maxn][maxn];
int n,m;
inline void f(int i, int j)
{
if(t[i][j]!=0)
{
if(t[i][j]==1){f(i-1, j-1);printf("%d ", a[i]);}
if(t[i][j]==2) f(i-1, j);
if(t[i][j]==3) f(i, j-1);
}
}
void solve()
{  
int i, j;
for(i=1;i<=n;++i)
for(j=1;j<=m;++j)
if(a[i]==b[j])
dp[i][j]=dp[i-1][j-1]+1,t[i][j]=1;
else
if(dp[i-1][j]>dp[i][j-1])
dp[i][j]=dp[i-1][j], t[i][j]=2;
else dp[i][j]=dp[i][j-1],t[i][j]=3;
freopen("cmlsc.out","w",stdout);
printf("%d\n", dp[n][m]);
f(n,m);
}
int main()
{
freopen("cmlsc.in","r",stdin);
scanf("%d %d\n", &n, &m);
int i;
for(i=1;i<=n;++i) scanf("%d ", a+i);
for(i=1;i<=m;++i) scanf("%d ", b+i);
solve();
return 0;
}