#include <bits/stdc++.h>
using namespace std;
 
int main() {
 
	int n;
	cin>>n;
 
	vector<int>target(n),cur(n);
 
	for(int i=0;i<n;i++){
		cin>>target[i];
	}
 
	for(int i=0;i<n;i++){
		cin>>cur[i];
	}
 
	unordered_map<int,int>pos;
	for(int i=0;i<n;i++){
		pos[cur[i]]=i;
	}
 
	int longest=0;
	int i=0;
	while(i<n){
		int count=1;
		int j=i;
 
		while(j<n-1){
			if(pos[target[j]]<pos[target[j+1]]){
				count++;
			}else{
				break;
			}
			j++;
		}
		longest=max(longest,count);
		i=j+1;
	}
	cout<<n-longest<<endl;
	return 0;
 
}

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

Ngo0IDIgMyAxIDUgNgozIDEgNCA2IDUgMiA=

6
4 2 3 1 5 6
3 1 4 6 5 2