Given a vector D and a same-size integer vector S of subset indices, return the mean of D within each subset:

• entry i is the mean of the D values whose S entry equals i
• i runs from 0 up to the largest value in S

Input

D = [0. 1. 2. 3. 4. 5. 6. 7. 8. 9.]
S = [0 1 2 3 0 1 2 3 0 1]

Output

[4. 5. 4. 5.]