select evtType, min(evttime), max(evttime) from (
select (arrayJoin([(1,'evt1'),(2,'evt1'),(3,'evt2'), (4,'evt2')]) as arr).1 as evttime, arr.2 as evtType
) group by evtType 

SELECT
    pair[1]      AS first_action,
    pair[2]      AS second_action,
    timestamp[1] AS start,
    timestamp[2] AS end
FROM
(
    SELECT
        arraySplit((a,i)-> i % 2 = 1, groupArray(action) as actions,arrayMap(a->if(a='s',1,2), actions) as ind) as pairs,
        arraySplit((t,i)-> i % 2 = 1, groupArray(time),ind) as timestamps
    FROM
    (
        SELECT
            now() + t AS time,
            action
        FROM system.one
        ARRAY JOIN
            [1,2,3,4,5,6,7,8,9,10] AS t,
            ['s','1','7','e','8','s','6','e','s','e'] AS action
        ORDER BY time
    )
    WHERE action in ('s','e')
)
ARRAY JOIN
    pairs AS pair,
    timestamps AS timestamp

SELECT
    now() + t AS time,
    action
FROM system.one
ARRAY JOIN
    [1,2,3,4,5,6,7,8,9,10] AS t,
    ['s','1','7','e','8','s','6','e','s','e'] AS action
ORDER BY time