#include <bits/stdc++.h>
#pragma GCC optimize("-O2")
using namespace std;
void err(istream_iterator<string> it) { cerr << endl; }
template <typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
  cerr << *it << " = " << a << "\t";
  err(++it, args...);
}
template <typename T1, typename T2>
ostream& operator<<(ostream& c, pair<T1, T2>& v) {
  c << "(" << v.first << "," << v.second << ")";
  return c;
}
template <template <class...> class TT, class... T>
ostream& operator<<(ostream& out, TT<T...>& c) {
  out << "{ ";
  for (auto& x : c) out << x << " ";
  out << "}";
  return out;
}
const int LIM = 1e6 + 5, MOD = 1e9 + 7;
const long double EPS = 1e-9;
int read() {
  int xx = 0, ff = 1;
  char ch = getchar();
  while (ch > '9' || ch < '0') {
    if (ch == '-') ff = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    xx = (xx << 3) + (xx << 1) + ch - '0';
    ch = getchar();
  }
  return xx * ff;
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n;
pair<long long, long long> pt[LIM];
int x[LIM], y[LIM];
int m[LIM], m2[LIM];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> x[i];
    x[i]--;
    m[x[i]] = i;
  }
  for (int i = 0; i < n; ++i) {
    cin >> y[i];
    y[i]--;
    m2[y[i]] = i;
  }
  for (int i = 0; i < n; ++i) pt[i] = make_pair(m[i], m2[i]);
  sort(pt, pt + n);
  set<int> s;
  set<int>::iterator it;
  for (int i = 0; i < n; ++i) {
    s.insert(MOD - pt[i].second);
    it = s.upper_bound(MOD - pt[i].second);
    if (it != s.end()) {
      s.erase(it);
    }
  }
  cout << s.size() << '\n';
  return 0;
}
