#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
const int LLINF = 0x3f3f3f3f3f3f3f3fLL;
int a[N], b[N], dp[3010][3010];
signed main(){
	int n;
	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++){
		int maxx = 1;
		for(int j = 1 ; j <= n ; j++){
			dp[i][j] = dp[i - 1][j];
			if(a[i] == b[j]) dp[i][j] = max(dp[i][j], maxx);
			if(a[i] > b[j]) maxx = max(maxx, dp[i - 1][j] + 1);
		}
	}
	int ans = 0;
	for(int i = 1 ; i <= n ; i++){
		ans = max(ans, dp[n][i]);
	}
	cout << ans << endl;
	return 0;
}