Formula to count number of nights falling in each month from arrival and departure dates

Hi,
Try this:

W2=IF((MONTH($L2)=COLUMN(W$1)-22)*(MONTH($M2)=COLUMN(W$1)-22),$M2-$L2,IF((MONTH($L2)=COLUMN(W$1)-22),EOMONTH($L2,0)-$L2+1,IF(MONTH($M2)=COLUMN(W$1)-22,$M2-EOMONTH($L2,0)-1,"")))

Because : Column(W$1)=23, jan= Column(W$1)-22....