A commercial kitchen logs a timestamped event every time a station begins or finishes preparing an order. Each order is prepared by exactly one station and generates exactly two log entries at that station: one start event and one end event, both carrying the same order id. Given the full log, compute, for every station that appears in the log, the average preparation duration — end timestamp minus start timestamp — across all the orders it handled.

Input format

The first line contains a single integer n, the number of log entries (n is always even). Each of the next n lines contains four space-separated fields: station_id order_id event timestamp, where station_id and order_id are integers, event is the literal string start or end, and timestamp is a non-negative real number of seconds (given with up to 3 digits after the decimal point). For every (station_id, order_id) pair appearing in the log there is exactly one start entry and exactly one end entry — they may appear in either order within the log — and the end timestamp is always strictly greater than the matching start timestamp.

Output format

Print one line per distinct station_id that appears in the log, in ascending order of station_id: the station_id, a single space, then its average preparation duration formatted with exactly 3 digits after the decimal point.

Constraints

• 2 <= n <= 20000, and n is always even
• 0 <= station_id, order_id <= 100000
• 0 <= timestamp <= 1000000

10
0 0 start 0.712
0 0 end 1.520
0 1 start 3.140
0 1 end 4.120
1 0 start 0.550
1 0 end 1.550
1 1 start 0.430
1 1 end 1.420
2 0 start 4.100
2 0 end 4.512

0 0.894
1 0.995
2 0.412

4
0 5 start 0
0 5 end 10
0 6 start 2
0 6 end 8

0 8.000