# Hints: Divisibility by 2^n

Any number can be written as

```
num = 2^x * remain
```

What happens to the product? What is the criteria for divisibility by `2^n`

?

Suppose the exponent of 2 in the resulting product is `x`

. Then, you need

```
want = max(0, n - x)
```

Which index gives you the maximum benefit?

Compute the exponent of 2 for each index, sort them in descending order and greedily keep taking the largest exponent till you reach your goal.