#include <iostream>

const int MAX = 1024;
int dp[MAX + 1][MAX + 1], v[MAX + 1], v2[MAX + 1], vrez[MAX];
char prec[MAX + 1][MAX + 1];
int main()
{
    FILE *fin, *fout;
    int n, m, i, j, nr;
    fin = fopen("cmlsc.in", "r");
    fscanf(fin, "%d%d", &n, &m);
    for (i = 1; i <= n; i++) {
        fscanf(fin, "%d", &v[i]);
    }
    for (i = 1; i <= m; i++) {
        fscanf(fin, "%d", &v2[i]);
    }
    fclose(fin);
    for (i = 1; i <= n; i++) {
        for (j = 1; j <= m; j++) {
            dp[i][j] = dp[i - 1][j];
            prec[i][j] = 1;
            if (dp[i][j - 1] > dp[i][j]) {
                dp[i][j] = dp[i][j - 1];
                prec[i][j] = 2;
            }
            if (v[i] == v2[j] && dp[i - 1][j - 1] + 1 > dp[i][j]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
                prec[i][j] = 3;
            }
        }
    }
    i = n;
    j = m;
    nr = 0;
    while (i > 0 && j > 0) {
        if (prec[i][j] == 3) {
            vrez[nr] = v[i];
            nr++;
            i--;
            j--;
        } else if (prec[i][j] == 2) {
            j--;
        } else {
            i--;
        }
    }
    fout = fopen("cmlsc.out", "w");
    fprintf(fout, "%d\n", nr);
    for (i = nr - 1; i >= 0; i--) {
        fprintf(fout, "%d ", vrez[i]);
    }
    fclose(fout);
    return 0;
}