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: 4135 sottrazione 5554 sottrazione 628 sottrazione 8854 aggiunta 6649 aggiunta 6272
A: 
2020