#include 
#include 
#include 
using namespace std;

int main() {
    int k, n;
    cin >> k >> n;
    vector 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 L = 0, R = n;
        
        while(L < R) {
            int middle = L + (R - L) / 2;
            if(x <= b[middle]) {
                R = middle;
            }
            else {
                L = middle + 1;
            }
        }
        if(L < n and b[L] < x) {
            L++;
        }
        if(b[L] >= x) {
            result += (n - L);
        }
    }
    cout << result << endl;
    return 0;
}
// 2 2 3 3 4 4