#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <map>
using namespace std;
typedef long long ll;

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 answer = 0;
    for(int i = 0; i < n; i++) {
        int fali = k - a[i];

            int indeks = lower_bound(b, b + n, fali) - b;
            if(indeks >= 0 and indeks < n) {
                answer += (n - indeks);
            }
    }
    cout << answer << endl;
    return 0;
}

/*

 4 5
 7 5 3 4 2
 4 3 2 2 1

 k = 4

 2, 3, 4, 5, 7
 1, 2, 2, 3, 4
 **/