complex countif question

I'm trying to find a formula to count how many times a cell on one column is lower than the cell in a different column. Example:

col A B

23 24
32 31
26 27
44 41
15 21
52 67

In the above example, the formula would return an answer of 2. Two times the value in B was lower than the value in A.

TIA for any workable suggestions.

D1=sumproduct(--(b1:b6<a1:a6))

Awesome thanks!

You are welcome