#include<bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
int a[200005];
int b[200005];
vector<int>id[200005];
vector<int>v;
vector<pair<int,int>>op;
int n;
struct segtree{
    int mx[400005];
    void upd(int st,int en,int i,int pos,int val){
        if(st>pos||en<pos)return;
        if(st==en)return void(mx[i]=val);
        int m=(st+en)/2;
        upd(st,m,i*2,pos,val);
        upd(m+1,en,i*2+1,pos,val);
        mx[i]=max(mx[i*2],mx[i*2+1]);
    }
    int fans(int st,int en,int i,int l,int r){
        if(st>r||en<l)return 0;
        if(st>=l&&en<=r)return mx[i];
        int m=(st+en)/2;
        return max(fans(st,m,i*2,l,r),fans(m+1,en,i*2+1,l,r));
    }
    void build(int st,int en,int i){
        if(st==en)return void(mx[i]=a[st]);
        int m=(st+en)/2;
        build(st,m,i*2);
        build(m+1,en,i*2+1);
        mx[i]=max(mx[i*2],mx[i*2+1]);
    }
}tr;
struct fenwick{
    int info[100005];
    void upd(int id,int val){
        for(int i=id;i<=n;i+=i&-i)info[i]=max(info[i],val);
    }
    int fans(int id){
        int ans=0;
        for(int i=id;i>0;i-=i&-i)ans=max(ans,info[i]);
        return ans;
    }
}fw;
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++)cin>>a[i],v.push_back(a[i]);
    for(int i=1;i<=n;i++)cin>>b[i],v.push_back(b[i]);
    sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
    for(int i=1;i<=n;i++){
        int x=lower_bound(v.begin(),v.end(),a[i])-v.begin()+1;
        a[i]=x;
        x=lower_bound(v.begin(),v.end(),b[i])-v.begin()+1;
        b[i]=x;
    }
    tr.build(1,n,1);
    for(int i=1;i<=n;i++){
        id[a[i]].push_back(i);
    }
    for(int i=1;i<=n;i++){
        vector<pair<int,int>>top;
        for(auto x:id[b[i]]){
            int mx=tr.fans(1,n,1,min(i,x),max(i,x));
            if(mx>b[i])continue;
            top.push_back({i,x});
        }
        reverse(top.begin(),top.end());
        for(auto x:top)op.push_back(x);
    }
    //sort(op.begin(),op.end());
    int ans=0;
    for(auto [x,y]:op){
        //cerr<<x<<" "<<-y<<"\n";
        int val=fw.fans(y)+1;
        ans=max(ans,val);
        //cerr<<val<<"\n";
        fw.upd(y,val);
    }
    cout<<ans;
}
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