#include <cstdio>
#include <iostream>
#include <algorithm>

#define N 5005

using namespace std;

int n, m, a[N], b[N], dp[N];

int main() {
    freopen("interview.in", "r", stdin);
    freopen("interview.out", "w", stdout);

    cin >> n >> m;
    for (int i = 0; i < n; i++)
        cin >> a[i];

    for (int j = 0; j < m; j++)
        cin >> b[j];

    for (int i = 0; i < n; i++) {
        for (int pos1 = 0, pos2 = 0, mx = 1; pos1 < m; pos1++) {
            while (b[pos1] != a[i] && pos1 < m) pos1++;
            if (pos1 == m) continue;

            for (; pos2 < pos1; pos2++)
                if (b[pos2] < b[pos1])
                    mx = max(mx, dp[pos2] + 1);

            dp[pos1] = max(dp[pos1], mx);
        }
    }

    int ans = 0;
    for (int i = 0; i < m; i++)
        ans = max(ans, dp[i]);
    cout << ans << endl;

    return 0;
}