Bobby has to do n chores today. i-th chore takes a[i] unit of time to complete. It is guaranteed that for every i, the condition a[i] >= a[i]-1 is met, so the sequence is sorted.
Also, Bobby can work hard on some chores. He can choose no more than k chores and do each in x units of time instead of a[i].
Bobby is very responsible, so he has to do all n chores, and now he wants to know the minimum time he needs to do everything. Bobby cannot do two chores simultaneously.
For example, given that:
k = 2, x = 2 and a = [4, 6, 7, 10]
The function should return 14
Since two chores, 7 and 10, can be done in 2 units of time, thus 2+2+4+6 = 14