#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  while (~scanf("%d", &n)) {
    int x1, y1, x2, y2;
    int ans = 0;
    for (int i = 0; i < n; i++) {
      scanf("%d %d %d %d", &x1, &y1, &x2, &y2);
      ans += (abs(x2 - x1) + 1) * (abs(y2 - y1) + 1);
    }
    printf("%d\n", ans);
  }
  return 0;
}
