/************************************
Note Book:
************************************/
#include <iostream>
#include <cstdio>
#include <iomanip>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <string>
#include <stack>
#include <queue>
#include <math.h>
#define LL long long
using namespace std;
const int INF = 0x3f3f3f3f;
const int MAXN = 5010;
int n , a[MAXN] , b[MAXN] , dp[MAXN] , maxn;
int main()
{
	cin >> n;
	for(int i = 1; i <= n; i++)
	{
		cin >> a[i];
	}
	for(int i = 1; i <= n; i++)
	{
		cin >> b[i];
	}
	for(int i = 1; i <= n; i++)
	{
		maxn = 0;
		for(int j = 1; j <= n; j++)
		{
			if(b[j] < a[i] && maxn < dp[j])
			{
				maxn = dp[j];
			}
			if(b[j] == a[i])
			{
				dp[j] = maxn + 1;
			}
		}
	}
	maxn = 0;
	for(int i = 1 ; i <= n ; i++ )
	{
		if(maxn < dp[i])
		{
			maxn = dp[i];
		}
	}
	cout << maxn;
	return 0;
}