Comparing Then Adding

say i have 4 columns of 5 values each consisting of 0's and 1's.

...a b c d
v 0 1 1 1
w 1 0 0 1
x 1 1 1 1
y 0 0 1 0
z 1 1 0 0


how would i write a function that would compare each value under column 'a' to each value under column 'b' and then return a value of 1 if they are equal, and return a value of 0 if they are not equal, then add up the return values.

(comparing column 'a' with 'b' you would get a result of 3.) then have the function continue on to compare column 'a' with column 'c'..'d; comparing column 'b'..'d', etc

so in long form: IF(av=bv,1,0) = 0
IF(aw=bw,1,0) = 0
IF(ax=bx,1,0) = 1
IF(ay=by,1,0) = 1
IF(az=bz,1,0) = 1

SUM(IFs) = 3