#include <stdio.h>

#define N 1024

FILE *in, *out;
int a[N+1], b[N+1], l_max[N+1][N+1], m, n;

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

void refac_subsirul(int l, int c) {
    if (l_max[l][c] == 0) {
        return;
    }
    if (a[l] == b[c]) {
        refac_subsirul(l - 1, c - 1);
        fprintf(out, "%d ", a[l]);
    } else {
        if (l_max[l-1][c] > l_max[l][c-1]) {
            refac_subsirul(l - 1, c);
        } else {
            refac_subsirul(l, c - 1);
        }
    }
}

int main(void) {
    in = fopen("cmlsc.in", "r");
    fscanf(in, "%d%d", &m, &n);
    for (int i = 1; i <= m; i++) {
        fscanf(in, "%d", &a[i]);
    }
    for (int j = 1; j <= n; j++) {
        fscanf(in, "%d", &b[j]);
    }
    fclose(in);
    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            if (a[i] == b[j]) {
                l_max[i][j] = 1 + l_max[i - 1][j - 1];
            } else {
                l_max[i][j] = max(l_max[i - 1][j], l_max[i][j - 1]);
            }
        }
    }
    out = fopen("cmlsc.out", "w");
    fprintf(out, "%d\n", l_max[m][n]);
    refac_subsirul(m, n);
    fclose(out);
    return 0;
}