#include <bits/stdc++.h>
#define endl '\n'
using namespace std;

typedef long long ll;

const int N =100010;
int a[N], b[N], c[N], dp[N];
int n;

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		c[a[i]] = i;
	}
	for (int i = 1; i <= n; i++)
		cin >> b[i];

	int len = 1;
	dp[1] = c[b[1]];

	for (int i = 2; i <= n; i++) {
		if (c[b[i]] > dp[len]) {
			dp[++len] = c[b[i]];
		} else {
			int l = 1, r = len;
			while (l <= r) {
				int mid = (l + r) / 2;
				if (dp[mid] >= c[b[i]]) {
					r = mid - 1;
				} else {
					l = mid + 1;
				}
			}
			dp[l] = c[b[i]]; 
		}
	}
	cout << len << endl;
	return 0;
}