#include<iostream>

 #include<cstdio>

 #include<cstring>

 #include<algorithm>

 #define maxn 100000+10

 #define INF 9187201950435737471

 #define rep(i,s,e) for(register int i=s;i<=e;++i)

 #define dwn(i,s,e) for(register int i=s;i>=e;--i)

 using namespace std;

 inline int read()

 {

     int x=;

     bool f=;

     char c=getchar();

     for(; !isdigit(c); c=getchar()) if(c=='-') f=;

     for(; isdigit(c); c=getchar()) x=(x<<)+(x<<)+c-'';

     if(f) return x;

     return -x;

 }

 inline void write(int x)

 {

     if(x<){putchar('-');x=-x;}

     if(x>)write(x/);

     putchar(x%+'');

 }

 int n,ans=;

 int a[maxn],b[maxn],book[maxn],last[maxn];

 signed main()

 {

     n=read();

     rep(i,,n) a[i]=read(),book[a[i]]=i;

     rep(i,,n) b[i]=read();

     last[]=book[b[]];

     rep(i,,n)

     {

         if(book[b[i]]>=last[ans]) last[++ans]=book[b[i]];

         else

         {

             int num=upper_bound(last+,last+ans+,book[b[i]])-last;

             last[num]=book[b[i]];

         }

     }

     write(ans);

     return ;

 }