#include<bits/stdc++.h>
#define ll long long
#define f first
#define s second
#define N 1025
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");
int a[N], b[N], dp[N][N], c[N];
int main(){
    int n,m,i,j,x;
    in>>n>>m;
    for(i=1; i<=n; ++i)
        in>>a[i];
    for(i=1; i<=m; ++i)
        in>>b[i];
    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;
            else
                dp[i][j]=max(dp[i-1][j], dp[i][j-1]);
        }
    }
    out<<dp[n][m]<<"\n";
    bool da=0;
    x=dp[n][m]+1, i=n, j=m;
    while(dp[i][j]){
        da=0;
        if(dp[i][j-1]>=x-1) --j,da=1;
        if(dp[i-1][j]>=x-1) --i,da=1;
        if(!da) c[--x]=b[j]; 
    }
    for(i=1; i<=dp[n][m]; ++i) out<<c[i]<<" ";
    return 0;
}