can psytoolkit use integer part of a number

Dear all,
I need to alternate two types of task (which differ in stimulus list to be randomly presented), but can not find how to count remainder for defining odd and even trials. Modulo operator works only with surveys.

task typeAtypeB
set $typeA random 1 8
set $typeB random 1 8
while $typeA == &previoustyppeA || $typeB == &previoustypeB 
set $typeA random 1 8
set $typeB random 1 8
while-end
set &previoustypeA $typeA
set &previoustypeB $typeB
set $typeBbitmap expression $typeB + 8 #refer to bitmaps from 9 to 16
keys a l
set $oddeven expression (TRIALCOUNT - 2 * integer(TRIALCOUNT / 2))
if $oddeven == 0
set %stimulus $typeA
else
set %stimulus $typeB
fi
show text %stimulus 0 0 white
save KEY RT STATUS