#include <cstdio>
#include <cstring>

using namespace std;

int n, m, l, a[1024], b[1024];
int d[1024][1024], v[1024];
void read () {
    scanf ("%d%d", &n, &m);
    int i;
    for (i=1; i<=n; ++i)
        scanf ("%d", &a[i]);
    for (i=1; i<=m; ++i)
        scanf("%d", &b[i]);
}

inline int maxim (int x, int y) {
    return x>y ? x : y;
}

void solve() {
    memset(d, 0, n*m*sizeof(int));
    int i, j;
    for (i=1; i<=n; ++i)
        for (j=1; j<=m; ++j)
            if (a[i]==b[j])
                d[i][j] = d[i-1][j-i]+1;
            else
                d[i][j] = maxim(d[i-1][j], d[i][j-1]);

}

void construct () {
    int j, k;
    for (l=0,j=n,k=m; d[j][k]!=0; )
        if (a[j]==b[k]) {
            v[l++] = a[j];
            --k; --j;
        }
        else
            if (d[j][k]==d[j-1][k])
                --j;
            else
                --k;

}

void write () {
    printf("%d\n", l);
    for (int i=l-1; i>=0; --i)
        printf("%d ",v[i]);
    printf("\n");
}

int main () {
    freopen("clmsc.in", "r", stdin);
    read();
    fclose(stdin);
    solve();
    construct();
    freopen("clmsc.out", "w", stdout);
    write();
    fclose(stdout);
    return 0;
}