File Storage and Tag Query

You are given a file tagging system where you can add tags to files and query files based on their tags. Each file is identified by a unique integer file ID. There are two types of operations:

• Add Operation: + file_id tag. This operation adds the specified tag to the file with the given ID.
• Query Operation: ? tag1 tag2 .... This operation queries for all file IDs that have all the specified tags. The result should be the list of matching file IDs in ascending order, printed as space-separated numbers. If no file matches, output None.

The input will be provided via standard input (stdin) with the following format:

n
operation1
operation2
...
operationn

where n is the number of operations.

inputFormat

The first line contains an integer n representing the total number of operations. Each of the next n lines contains an operation in one of the following formats:

• + file_id tag for adding a tag to a file.
• ? tag1 tag2 ... for querying files that have all the given tags.

All input is read from stdin.

outputFormat

For each query operation, output a single line containing the resulting file IDs in ascending order separated by a single space. If no file matches the query, output None (without quotes). All output should be sent to stdout.

## sample

6
+ 1 design
+ 1 database
+ 2 design
+ 2 backend
+ 3 database
? design database

1

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