td/leaderboard problem

[doin]

I've got a problem with my td.
I want to substract lives from the total of 25 lives every time a unit enters a region.
I've got the leaderboard working, but i don't know how to substract.
In other words:
When unit from player grey enters end region red: substract 1 from total lives.

 

[SFilip]

make a new integer variable called lives (the variable editor is a part of the trigger editor)
then when a unit enters your defeat region set lives = lives - 1 (action under general - set variable)
then change the leaderboard value to lives.