#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
const int INF = 2147483645;
const int maxN = (int)1e5+5;
const ll LLINF = LLONG_MAX;
//const ll mod = 998244353;
const ll mod = 1000000007;
ll dp[maxN];
vector<int> v;
ll lis (ll n) {
ll mx = 0;
for (int i=0; i<n; i++) {
for (int j=0; j<i; j++) {
if (v[i] >= v[j]) {
dp[i] = max(dp[i], dp[j] + 1);
}
}
}
for (int i=0;i<n;i++) {
mx = max(mx, dp[i]);
}
return mx+1;
}
void st3(vector<int> h, vector<int> t) {
map<int, int> idx;
int n = h.size();
for (int i=0;i<n;i++) idx[h[i]] = i;
for (int i=0;i<n;i++) {
if (idx.count(t[i]) && i <= idx[t[i]]) v.pb(t[i]);
}
cout<<lis(v.size());
}
void solv() {
int n, a, ans=0;
vector<int> h, t;
bool inc = true;
cin>>n;
for (int i=0;i<n;i++) {
cin>>a, h.pb(a);
if (i > 0) {
if (a <= h[i-1]) inc = false;
}
}
for (int i=0;i<n;i++) cin>>a, t.pb(a);
if (inc) {
st3(h, t);
return;
}
for (int i=0;i<n;i++) {
if (h[i] != a) continue;
int tmp = i-1;
while (tmp >= 0 && h[tmp] <= a) {
ans++, tmp--;
}
while (i < n && h[i] <= a) {
ans++, i++;
}
}
cout<<ans<<'\n';
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
int t=1;
// cin>>t;
while (t--) solv();
}
