Calculated item for two another items.

[Voland]

I need make calculated item, which get maximum value of two items.

for example, I have items:
proc_info[<my exe process>,vmsize,sum]
and
proc_info[<my exe process>,wkset,sum]
New calculated item must have value which maximum of thic items.

Is it posable?
(zabbix 2.4.x)