The Ant Man

/*
 * Author   :   jignesh1604
 * Link : https://www.hackerearth.com/problem/algorithm/the-ant-man-73f27925/
 */


#include<bits/stdc++.h>
using namespace std;
#define FAST ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);

#define pb push_back
#define sz size()
#define ff first
#define ss second
#define ll long long int
#define ld long double
#define bp __builtin_popcountll
#define FOR(i,a,b) for(i=a;i<b;i++)
#define ROR(i,a,b) for(i=a;i>b;i--)
#define FORE(i,a,b) for(i=a;i<=b;i++)
#define RORE(i,a,b) for(i=a;i>=b;i--)
#define pii pair<int,int>
#define pll pair<ll,ll>
const ll M=1e9+7;

bool isprime(ll n)
{
    for(ll i=2;i<=sqrt(n);i++)
    {
        if(n%i==0)
            return false;
    }
    return true;
}

bool sortbysec(const pair<ll,ll> &a,const pair<ll,ll> &b)
{
    if(a.first<b.first)
        return true;
    else
        return false;
}

// fflush(stdout)

int main()
{
    FAST;
    ll n,i,j,ans=0,x;
    cin>>n;
    queue<ll> a,b;
    FOR(i,0,n)
    {
        cin>>x;
        a.push(x);
    }
    FOR(i,0,n)
    {
        cin>>x;
        b.push(x);
    }
    map<ll,ll> mp;
    while(!a.empty())
    {
        if(mp[a.front()]==1)
        {
            a.pop();
        }
        else if(a.front()==b.front())
        {
            a.pop();
            b.pop();
        }
        else
        {
            ans++;
            mp[b.front()]=1;
            b.pop();
        }
    }
    cout<<ans<<"\n";
}