#include <iostream>
#include <iomanip>
#include <vector>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cmath>

using namespace std;

#pragma comment (linker, "/stack:250000000")

#define MAXN 5010

int main()
{
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);

    int n, m, i, j, k, a[MAXN], b[MAXN], len[MAXN][MAXN] = {}, mx[MAXN][MAXN] = {};

    cin >> n >> m;

    for (i = 1; i <= n; i++)
        cin >> a[i];

    for (i = 1; i <= m; i++)
        cin >> b[i];

    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
            if (a[i] == b[j])
            {
                if (a[i] > mx[i-1][j-1])
                {
                    mx[i][j] = a[i];
                    len[i][j] = len[i-1][j-1] + 1;
                }
                else
                    if (len[i-1][j] > len[i][j-1])
                    {
                        mx[i][j] = mx[i-1][j];
                        len[i][j] = len[i-1][j];
                    }
                    else if (len[i-1][j] < len[i][j-1])
                    {
                        mx[i][j] = mx[i][j-1];
                        len[i][j] = len[i][j-1];
                    }
                    else if (mx[i-1][j] < mx[i][j-1])
                    {
                        mx[i][j] = mx[i-1][j];
                        len[i][j] = len[i-1][j];
                    }
                    else
                    {
                        mx[i][j] = mx[i][j-1];
                        len[i][j] = len[i][j-1];
                    }
            }
            else
                if (len[i-1][j] > len[i][j-1])
                {
                    mx[i][j] = mx[i-1][j];
                    len[i][j] = len[i-1][j];
                }
                else if (len[i-1][j] < len[i][j-1])
                {
                    mx[i][j] = mx[i][j-1];
                    len[i][j] = len[i][j-1];
                }
                else if (mx[i-1][j] < mx[i][j-1])
                {
                    mx[i][j] = mx[i-1][j];
                    len[i][j] = len[i-1][j];
                }
                else
                {
                    mx[i][j] = mx[i][j-1];
                    len[i][j] = len[i][j-1];
                }

    cout << len[n][m];

    return 0;
}