Untitled

#include 
#include 
#include 
#include 
#include 
using namespace std;
int main(){
    int k, n;
    cin >> k >> n;
    int a[n];
    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }
    int b[n];
    for(int i = 0; i < n; i++) {
        cin >> b[i];
    }
    sort(a, a + n);
    sort(b, b + n);
    long long answer = (long long)n * (long long)n;
    for(int i = 0; i < n; i++) {
        int fali = k - a[i];
        if(fali >= 0) {
            int indeks = upper_bound(b, b + n, fali - 1) - b;
            if(indeks >= 0 and indeks <= n) {
                answer -= indeks;
            }
        }
    }
    cout << answer << endl;
    return 0;
}

/*
 5 * 5 = 25
 25 - 1 = 24
 7 5 3 4 2
 4 3 2 2 1
 
 4 - 2 = 2;
 2, 3, 4, 5, 7
 1, 2, 2, 3, 4
 
 **/