import math


def OOC_calc(TP, TOP, P):
    """
    Calculate Otsuka-Ochiai coefficient (OOC).

    :param TP: true positive
    :type TP: int
    :param TOP: number of positives in predict vector
    :type TOP: int
    :param P: number of actual positives
    :type P: int
    :return: OOC as float
    """
    try:
        OOC = TP / (math.sqrt(TOP * P))
        return OOC
    except (ZeroDivisionError, TypeError, ValueError):
        return "None"