Clashing seat bookings with a record

Problem

A booking app stores each seat as record Seat(String coach, int number). Two bookings clash when they are for the same coach and the same seat number. Count the bookings that repeat a seat booked earlier, comparing seats with equals().

Input, output and limits

Input: The first line has n. Each of the next n lines has a coach (like B2) and a seat number.
Output: Clashes <count>.
Constraints: 1 ≤ n ≤ 1000
A coach is 1 to 3 letters and digits
1 ≤ seat number ≤ 72

Examples

Example

Input

Output

Clashes 2

The third and the fifth bookings repeat B2 14.

Hints

Try the problem first. Open one hint at a time.

Hint 1

A record's generated equals() compares every component, so new Seat("B2", 14).equals(new Seat("B2", 14)) is true.

Hint 2

For booking i, look back at bookings 0 to i − 1; count i once if any of them is equal.

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