PermutariAB

#include <bits/stdc++.h>

#define Nmax 100005
#define ll long long

using namespace std;

ifstream fin("permutariab.in");
ofstream fout("permutariab.out");

int N;
int A[Nmax];
int B[Nmax];
int pos[Nmax];

ll mergesort(int le, int ri)
{
    if(le == ri)
        return 0;
    int mid = (le + ri) / 2;
    ll ret = mergesort(le, mid) + mergesort(mid + 1, ri);
    int pos = le;
    int j = mid + 1;
    for(int i = le; i <= mid; i++)
    {
        while(j <= ri && A[j] < A[i])
            B[pos++] = A[j++];
        ret += j - mid - 1;
        B[pos++] = A[i];
    }
    while(j <= ri)
        B[pos++] = A[j++];
    for(int i = le; i <= ri; i++)
        A[i] = B[i];
    return ret;
}

int main()
{
    fin >> N;
    for(int i = 1; i <= N; i++)
    {
        int x;
        fin >> x;
        pos[x] = i;
    }
    for(int i = 1; i <= N; i++)
    {
        int x;
        fin >> x;
        A[i] = pos[x];
    }
    fout << mergesort(1, N) << "\n";
    return 0;
}