Codeforces

627D.cpp

#include<bits/stdc++.h>
 
#define endl "\n";
using namespace std;
typedef long long ll;
 
int arr[200001], inf = 1000000000;
 
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n; cin >> n;
  for (int i = 0; i < n; i++)     cin >> arr[i];
  for (int i = 0; i < n; i++) {
    int x; cin >> x;
    arr[i] -= x;
  }
  sort(arr, arr + n);
  ll ans = 0;
  for (int i = 0; i < n; i++) {
    ll idx = upper_bound(arr + i + 1, arr + n, inf) - lower_bound(arr + i + 1, arr + n, -arr[i] + 1);
    ans += idx;
  }
  cout << ans;
}