Organize Stamp Collection

Given a series of test cases, each consisting of a collection of stamps represented by their country codes and rarity levels, your task is to compute two things for each test case:

• The number of distinct countries in the collection.
• The average rarity level for the stamps of each country. The average should be computed as \(\frac{\text{sum of rarity levels}}{\text{number of stamps}}\) and displayed with two decimal places.

The country codes must be output in alphabetical order.

Example:

Input:
1
4
USA 50
IND 70
USA 20
IND 30
Output:
2
IND 50.00
USA 35.00

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inputFormat

The input is read from stdin and has the following format:

1. The first line contains an integer T, the number of test cases.
2. For each test case, the first line contains an integer N representing the number of stamps.
3. This is followed by N lines, each containing a string for the country code and an integer for the rarity level (separated by a space).

outputFormat

For each test case, output the result to stdout in the following format:

1. The first line should contain the number of distinct countries.
2. This is followed by one line per country, which contains the country code and its average rarity level formatted to exactly two decimal places, separated by a space. The countries must be listed in alphabetical order.

## sample

1
4
USA 50
IND 70
USA 20
IND 30

2
IND 50.00
USA 35.00

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