In this task you will be given an arithmetic operation in Italian and you have to find its answer. The operations 'addition' and 'subtraction' have been replaced with their italian translations i.e you need to perform addition when you see 'aggiunta' and subtraction in case of 'sottrazione'.
Q: 8623 sottrazione 6971 sottrazione 4359 aggiunta 5259 aggiunta 8620
A: 
11172