Inventory Management System

In this problem, you are required to implement an inventory management system that processes a series of operations. The system should support the following three types of operations:

• add <item_id> <quantity>: Add the specified quantity to the given item. If the item already exists, increase its stock.
• remove <item_id> <quantity>: Remove the specified quantity from the given item. If the item does not exist, print Item not available. If the removal quantity exceeds the current stock, print Insufficient stock.
• check <item_id>: Check and print the current stock for the given item. If the item is not found, print Item not found.

The operations are applied in the order they are received. For every check operation and error messages arising from remove operations, output the corresponding message on a new line.

Note: All outputs should be printed to standard output.

inputFormat

The first line of input contains an integer n, denoting the number of operations.

Each of the following n lines contains a single operation, which can be one of the following formats:

• add item_id quantity
• remove item_id quantity
• check item_id

outputFormat

For every check operation as well as for error messages from remove operations, print the corresponding output on a new line.

If the operation is check and the item exists, output its current quantity. Otherwise, output the respective error message (Item not found, Item not available, or Insufficient stock).

## sample

5
add 101 50
add 102 25
remove 101 30
check 101
check 103

20
Item not found

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