#include <iostream>
#include<bits/stdc++.h>

using namespace std;

int main() {
	// your code goes here
	int n;
	cin>>n;
	vector<int> arr1(n);
	vector<int> arr2(n);
	for(int i=0;i<n;i++){
		cin>>arr1[i];
	}
	
	unordered_map<int,int> mpp;
	
	
	for(int i=0;i<n;i++){
		cin>>arr2[i];
		mpp[arr2[i]]=i;
	}
	
	int i=0;
	int j=0;
	int ans=0;
	int mini = INT_MIN;
	
	
	
	while(i<n && j<n){
		int a = arr1[j];
		int b = mpp[a];
		if(b>mini){
			mini=b;
			ans=max(ans,j-i+1);
			j++;
		}
		else{
			i=j;
			mini=INT_MIN;
		}
		
	}
	
	cout<<n-ans<<endl;
	
	
	
	return 0;
}