Count 3D Array Element

题面

统计 3D 整型数组中等于 p 的元素个数，结果写入 output。

Implementation Requirements

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

Examples

3D 数组示例一：p=1 → 5
示例二：p=1 → 0

Constraints

• 1 ≤ N, M, K ≤ 1,000
• 1 ≤ input[i], p ≤ 100
• Performance: N=500, M=500, K=500