#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define all(x) (x).begin(), (x).end()
bool be;
constexpr int N = 2e5 + 5;
int n;
struct node {
	int a, b;
}a[N];
bool en;
int main()
{
	cerr << (&be - &en) / 1024.0 / 1024 << " MB\n--------------------------------" << endl;
#ifdef IAKIOI
	freopen("in.in", "r", stdin);
//	freopen("out.out", "w", stdout);
#endif
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n;
	for (int i = 1; i <= n; ++i) cin >> a[i].a;
	for (int i = 1; i <= n; ++i) cin >> a[i].b;
	sort(a + 1, a + 1 + n, [](node a, node b) {
		return a.a < b.a;
	});
	set<int>S;
	for (int i = 1; i <= n; ++i) {
		auto it = S.lower_bound(a[i].b);
		if (it != S.end()) S.erase(it);
		S.emplace(a[i].b);
	}
	cout << S.size() << endl;
	return 0;
}