Problem 42803. Britney unfolded

You have a long, narrow strip of paper. You are going to fold this strip of paper length-wise in half, than fold the folded strip length-wise in half again, and repeat this process until it is no longer possible to do so.

You then unfold the strip of paper and count how many fold marks it bears.

Given the number of folds, n, and the thickness of the paper, t, return the minimum length, L, the strip of paper must be to accommodate n folds, as well as the number of fold marks, f. Note that strips of paper only come in integer lengths.

Assume t and L are given in the same units.

Example:

n = 3

t = 0.15

L = 7

f = 7