Session Manager

You are tasked with implementing a SessionManager that manages user sessions for a web application. Each session is identified by a unique session id and has an associated timestamp. The program must support the following operations:

• create session_id timestamp: Create a session with the given session_id and timestamp (an integer). If the session already exists, do nothing.
• update session_id new_timestamp: Update the timestamp of an existing session identified by session_id to new_timestamp.
• delete session_id: Delete the session identified by session_id if it exists.
• count start_timestamp end_timestamp: Count and output the number of sessions whose timestamp lies in the inclusive interval \( [start\_timestamp,\ end\_timestamp] \).

The input will consist of a series of operations. You must process each operation in order and for each count operation, output the result on a new line.

Note: All timestamps are integers. The conditions for counting use the inequality
\( start\_timestamp \leq timestamp \leq end\_timestamp \).

inputFormat

The first line contains an integer n representing the number of operations.

Each of the next n lines contains an operation in one of the following formats:

• create session_id timestamp
• update session_id new_timestamp
• delete session_id
• count start_timestamp end_timestamp

outputFormat

For each count operation, output the number of active sessions within the specified time frame on a new line.

## sample

9
create abc123 100
create def456 200
create ghi789 150
count 100 250
update abc123 300
count 100 350
delete ghi789
count 100 350
count 300 450

3
3
2
1

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