原题面：

ASK x1 y1 x2 y2 — Alesha wants to know the sum of pleasure values the lightbulbs, placed in a rectangular part of the field. Top-left cell of a part has coordinates (x1, y1) and right-bottom cell has coordinates (x2, y2). It is guaranteed that 1 ≤ x1 ≤ x2 ≤ n and 1 ≤ y1 ≤ y2 ≤ m. There is no more than 2000 events of this type in the input.

洛谷翻译：

选择网格的一个子矩阵，求这个子矩阵中的所有亮着的灯泡的快乐值之和。

“There is no more than 2000 events of this type in the input”为什么不翻译？