#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#pragma GCC optimize("Ofast,unroll-loops,inline-functions,no-stack-protector,03")
#pragma GCC target ("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx2,mmx,fma,avx,tune=native")
#pragma clang loop vectorize(enable)
#pragma clang loop interleave(enable)
#define int long long
#define sz(x) (int)x.size()
#define F first
#define S second
#define pb push_back
#define nl '\n'
#define o_set tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef pair<int, int> pii;
void file( string s = "" )
{
if( s.empty() )
return;
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
const int N = 2e5 + 2;
const int N1 = 1e6 + 2;
const int inf = 1e9 + 2;
const int INF = 1e18 + 2;
const int mod = 1e9 + 7;
int T = 1, n, a[N], b[N], t[N], l[N], r[N];
void upd( int i, int x )
{
for( ; i < N; i += i & -i )
t[i] = max(t[i], x);
}
int get( int i )
{
int res = 0;
for( ; i; i -= i & -i )
res = max(res, t[i]);
return res;
}
void solve()
{
cin >>n;
int cnt = 0;
stack< int > st;
vector< int > g[n + 1], vec;
for( int i = 1; i <= n; ++i )
{
cin >>a[i];
vec.pb(a[i]);
}
for( int i = 1; i <= n; ++i )
{
cin >>b[i];
vec.pb(b[i]);
if( b[i] == b[1] )
++cnt;
}
sort(vec.begin(), vec.end());
vec.erase(unique(vec.begin(), vec.end()), vec.end());
for( int i = 1; i <= n; ++i )
{
a[i] = lower_bound(vec.begin(), vec.end(), a[i]) - vec.begin() + 1;
b[i] = lower_bound(vec.begin(), vec.end(), b[i]) - vec.begin() + 1;
g[a[i]].pb(i);
}
a[0] = a[n + 1] = inf;
st.push(0);
for( int i = 1; i <= n; ++i )
{
while( a[st.top()] <= a[i] )
st.pop();
l[i] = st.top() + 1;
st.push(i);
}
while( !st.empty() )
st.pop();
st.push(n + 1);
for( int i = n; i >= 1; --i )
{
while( a[st.top()] <= a[i] )
st.pop();
r[i] = st.top() - 1;
st.push(i);
}
int ans = 0;
for( int i = 1; i <= n; ++i )
for( int j: g[b[i]] )
if( l[j] <= i && i <= r[j] )
{
int x = get(j) + 1;
ans = max(ans, x);
upd(j, x);
}
cout <<ans;
}
signed main()
{
file("");
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// cin >>T;
while( T-- )
solve();
}
