You are given a $2$D integer array students, where each element students[i] = [student_id, bench_id] represents that a student with identifier student_id is sitting on the bench with identifier bench_id.

Return the maximum number of unique students sitting on any single bench. If students is empty, return $0$.

Constraints:

• $0 \leq$ students.length $\leq 100$

• students[i] = [student_id, bench_id]

• $1 \leq$ student_id $\leq 100$

• $1 \leq$ bench_id $\leq 100$

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We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.