#include <iostream>

using namespace std;

int main() {
    int n, m;
    cin >> n >> m;

    int a[n], b[m];

    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }

    for (int j = 0; j < m; ++j) {
        cin >> b[j];
    }

    int i = 0, j = 0;
    int count = 0;

    while (i < n && j < m) {
        if (a[i] < b[j]) {
            ++i;
        } else if (a[i] > b[j]) {
            ++j;
        } else {
            int ai = a[i], bj = b[j];
            int aiCount = 0, bjCount = 0;

            while (i < n && a[i] == ai) {
                ++aiCount;
                ++i;
            }

            while (j < m && b[j] == bj) {
                ++bjCount;
                ++j;
            }

            count += aiCount * bjCount;
        }
    }

    cout << count << endl;

    return 0;
}