#include <iostream>
#include <algorithm>
using namespace std;

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

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

    sort(a, a + n);
    sort(b, b + n);


    long long res = 0;
    for(int i = 0; i < n; i++) {
        if(a[i] >= k) {
            res += n;
        }
        else {
            int idx = lower_bound(b, b + n, k - a[i]) - b;

            if(idx >= 0 and idx < n) {
                res += n - idx;
            }
        }
    }
    cout << res << endl;

    return 0;
}