#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;

const int N = 1e6+10;
int q[N],id[N];

int main(){
  int n;
  cin>>n;

  memset(id,-1,sizeof id);
  for(int i = 0;i<n;++i){
    int x;
    scanf("%d",&x);
    id[x] = i;
  }

  int tt = 0;
  q[0] = -1;
  for(int i = 0;i<n;++i){
    int x;
    scanf("%d",&x);
    int k = id[x];
    if(k == -1) continue;
    int l = 0,r = tt;
    while(l<r){
      int mid = l+r+1>>1;
      if(q[mid]< k) l = mid;
      else r = mid - 1;
    }

    q[r+1] = k;
    tt = max(tt,r+1);
  }

  cout<<tt<<endl;

  return 0;
}