#include <stdio.h>


int maxim(int a, int b) {
	if(a > b) {
		return a;
	}

	return b;
}


int main() {
	FILE *in = fopen("cmlsc.in", "r");
	int n, m;
	fscanf(in, "%d%d", &n, &m);

	int a[n], b[m];

	for(int i = 0; i < n; i++) {
		fscanf(in, "%d", &a[i]);
	}

	for(int i = 0; i < m; i++) {
		fscanf(in, "%d", &b[i]);
	}

	fclose(in);

	int dp[n + 1][m + 1];


	for(int i = 0; i <= n; i++) {
		for(int j = 0; j <= m; j++) {
			if(i == 0 || j == 0) {
				dp[i][j] = 0;
			} else if(a[i - 1] == b[j - 1]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			} else {
				dp[i][j] = maxim(dp[i - 1][j], dp[i][j - 1]);
			}
		}
	}

	FILE *out = fopen("cmlsc.out", "w");

	fprintf(out, "%d\n", dp[n][m]);
	int len = dp[n][m];

	int rezultat[len];
	int k = len - 1;

	int i = n;
	int j = m;

	while(i > 0 && j > 0) {
		if(a[i - 1] == b[j - 1]) {
			rezultat[k] = a[i - 1];
			i--;
			j--;
			k--;
		} else if (dp[i - 1][j] > dp[i][j - 1]) {
			i--;
		} else {
			j--;
		}
	}

	for(int i = 0; i < len; i++) {
		fprintf(out, "%d ", rezultat[i]);
	}

	fclose(out);
}