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'.

Example input: 10 sottrazione 7
Example output: 3
Example explanation: Here, 'sottrazione' represents the subtraction operation. So, the answer is 3 (10-7=3).
Q: 6427 sottrazione 9286 aggiunta 2242 aggiunta 6902 aggiunta 4937 aggiunta 9307
A:
20529