Formula needed for yes/no calculation

Hi, 
I am trying to create a formula with an IF function in Excel, but I can't seem to figure it out.<br><br>

Here's the "business case":<br>
I am trying to calculate the amount of spaces that need a specific component installed. <br><br>

There are 3 floors in the building:<br>
Floor 1 has 3 spaces<br>
Floor 2 has 4 spaces<br>
Floor 3 has 2 spaces<br><br>

That's a total of 9 spaces if I want to install a component in all of the spaces. But, I don't. That's why there are also fields with a Yes or No answer. Based on a Yes or No answer for a specific floor I need to calculate the components.<br><br>

The Fields in Excel are as follows:<br>
A2 contains the text "ground floor"<br>
A3 contains the text "1st floor"<br>
A4 contains the text "2nd floor"<br><br>

B2 contains the value "3"<br>
B3 contains the value "4"<br>
B4 contains the value "2"<br><br>

B5 contains the value "9" (=sum(B2:B4))<br><br>

C2 contains the text "yes"<br>
C3 contains the text "no"<br>
C4 contains the text "no"<br><br>

At this point I have figured out how to calculate the following:<br>
If C2 = Yes + C3 = Yes + C4 = Yes<br>
then the formula is: =IF(C2="yes";IF(C3="yes";IF(C4="no";B5)))<br>
the correct result is: 9<br><br>

If C2 = Yes + C3 = Yes + C4 = No<br>
then the formula is: =IF(C2="yes";IF(C3="yes";IF(C4="no";B5-B4)))<br>
the correct result is: 7<br><br>

If C2 = Yes + C3 = No + C4 = No<br>
then the formula is: =IF(C2="yes";IF(C3="no";IF(C4="no";B5-B4-B3)))<br>
the correct result is: 3<br><br>

Here's the question:<br>
I need a formula which combines the above three formula's into one. With this formula I need to be able to get an answer to all possible Yes/No combinations.<br><br>

Can anybody help me?