【 ssl2 ⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶⁶83

analysis ：

Longest common subsequence $upper\_bound$ Just find a place

CODE：

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#define reg register
using namespace std;
typedef long long ll;
const int N=1e5+5;
int n,id[N],a[N],f[N],ans;
int main(){
    
	scanf("%d",&n);
	for(int i=1,x;i<=n;i++)
	{
    
		scanf("%d",&x);
		id[x]=i;
	}
	for(int i=1,x;i<=n;i++)
	{
    
		scanf("%d",&x);
		a[i]=id[x]; 
	}
	f[++ans]=a[1];
	for(int i=2;i<=n;i++)
	{
    
		if(a[i]>f[ans]) f[++ans]=a[i];
		else 
		{
    
			int p=upper_bound(f+1,f+ans+1,a[i])-f;
			f[p]=a[i];
		}
	}
	printf("%d",ans);
	return 0;
}