Pair Programming

Time Limit	Memory Limit	Input File	Output File
5 seconds	256 MiB	`Standard Input`	`Standard Output`

Problem info

- Subtask 1 (20 points) has 10 cases.
- Subtask 2 (20 points) has 30 cases.
- Subtask 3 (20 points) has 49 cases.
- Subtask 4 (40 points) has 72 cases.
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