#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x1, y1, x2, y2, sum = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> x1 >> y1 >> x2 >> y2;
    for (int j = x1; j <= x2; j++)
      for (int k = y1; k <= y2; k++) sum++;
  }
  cout << sum;
  return 0;
}
