3D Subarray Sum

题面

计算三维数组子块 input[S_DEP..E_DEP][S_ROW..E_ROW][S_COL..E_COL] 的元素和（深度、行、列索引均为 0-based 含端点）。

Implementation Requirements

• Use only native features (external libraries are not permitted)
• The solve function signature must remain unchanged
• 结果写入 output

Examples

示例一：如页面所示 → 7
示例二：如页面所示 → 14

Constraints

• 1 ≤ N, M, K ≤ 500
• 1 ≤ input[i] ≤ 10
• 合法的 S/E 索引范围；Performance: N=M=K=500