record the total items from each sheet in a column called All Totals

[caretaker]

Hi everyone,
I am a bit stuck with an excel spreadsheet I do for work and would like to ask your advise, I will try to explain as best as I can.
I am running a small store that feeds 13 buildings.
On the spreadsheet there are 13 sheets, one for each building.
The items will go out monthly.
What I need to do is record the total items from each sheet in a column called All Totals on the first sheet, this will add up the totals for all the buildings.
If I put an attachment that may help out a bit.
If you can look at P3 it is all the P3s to add together, next down will be total of P4,P5,P6...
Good luck but if this can not be done it is not the end of the world.
Reg