#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
 
int main() {
    int k, n;
    cin >> k >> n;
    vector<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.begin(), a.end());
    sort(b.begin(), b.end());
    long long result = 0;
    for(int i = 0; i < n; i++) {
        int x = k - a[i];
        int idx = lower_bound(b.begin(), b.end(), x) - b.begin();
        if(idx >= 0 and idx < n) {
            result += n - idx;
        }
    }
    cout << result << endl;
    return 0;
}