A company currently pays a fixed sum for the use of a particular licensed software package.   In determining if it has a good deal it decides to calculate its maximum use of the software from its license management log file.

Assume the software's licensing daemon faithfully records a checkout event when a copy of the software starts and a checkin event when the software finishes to its log file.

An example of checkout and checkin events are:

 License OUT @ 2008/10/03_23:51:05 for job 4974
 ...
 License IN  @ 2008/10/04_00:18:22 for job 4974



Task

Save the 10,000 line log file from    here   into a local file, then write a program to scan the file extracting both the maximum licenses that were out at any time, and the time(s) at which this occurs.

Mirror of log file available as a zip here (offsite mirror).




   require 'files'
   'I D' =: (8 ; 14+i.19) {"1 &.> <'m' fread 'licenses.txt' NB.  read file as matrix, select columns
   lu    =:  +/\ _1 ^ 'OI' i. I                             NB.  Number of licenses in use at any given time
   mx    =:  (I.@:= >./) lu                                 NB.  Indicies of maxima
 
   NB.  Output results
   (mx { D) ,~ 'Maximum simultaneous license use is ' , ' at the following times:' ,~ ": {. ,mx { lu