#include <bits/stdc++.h>
using namespace std;
#define ll long long

void ez()
{
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#endif
}

bool comp(ll &a, ll &b)
{
    return a > b;
}

void solve()
{
    ll n, m, ans = 0;
    cin >> n >> m;
    vector<ll> a(n), b(m), h;
    for (auto &i : a)
        cin >> i;
    for (auto &i : b)
        cin >> i;
    ll f = 0, l = 0;

    while (f < n and l < m)
    {
        ll cnt = 0;
        while (l < m and b[l] < a[f])
        {
            l++;
        }
        while (a[f] == b[l])
        {
            cnt++;
            l++;
        }

        do
        {
            f++;
            ans += cnt;
        } while (a[f] == a[f - 1]);
    }

    cout << ans << endl;
}

int main()
{
    ez();
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}