6. (20 points) Concurrent Sums with Monitors int a, b, c, d, e cin >> a cin>b c-a+1 d-a+a e-d-b; cout a e; Your goal is to rewrite this program as a collection of threads, one for each line of code. (Each thread should call a monitor function that, possibly among other things, executes its line of code.) You must use monitors to retain the original sequential semantics of the code (i.e., the output must be identical to the same program where all statements are executed by the same thread). However you must also exploit the maximum amount of concurrency; when two statements can safe ly execute concurrently, you must let them do so