の[末「すえ」]/た[末「すえ」] => conclusion N2
Reason, Result, Response
終わる => to finish; to end N4
末 => finally; after; following; at the end/ conclusion of ~ N2
[時「とき」] => At the time A N5
Time
[終「お」]わる => To finish A; A ends N4
Secondary Verb
と同時に => at the same time as; while; simultaneously ~ N2
Vた[時「とき」] => After having done something N5
Time