#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];
    int cnt[105];
    for(int i = 0; i < 105; i++) {
        cnt[i] = 0;
    }
    for(int i = 0; i < n; i++) {
        cin >> a[i];
    }
    for(int j = 0; j < n; j++) {
        cin >> b[j];
        cnt[b[j]] += 1;
    }
    long long answer = 0;
    for(int i = 0; i < n; i++) {
        int potrebno = k - a[i];
        if(potrebno < 0) {
            potrebno = 0;
        }
        for(int j = potrebno; j <= 100; j++) {
            answer += cnt[j];
        }
    }
    cout << answer << endl;
    return 0;
}

/*

 a[i] + b[j] >= k
 k - a[i]

 **/