import math


def glue_library(vsize, completeness):
    """
    Find the required library size given:
    :param vsize: Number of possible variants
    :param completeness: completeness as [0,1] number
    :return: library size required
    """
    if completeness > 1:  # percentage...
        completeness /= 100
    return -vsize * math.log(1 - completeness)