def lyambda_fact_top(m_distrib, R):
    """
    Calculates the the factor of masstransfer.
    Parameters
    ----------
    m_distrib : float
        The distribution coefficient, [dismensionless]
    R : float
        The reflux number, [dismensionless]
    Returns
    -------
    lyambda_fact_top : float
        The factor of masstransfer, [dismensionless]
    References
    ----------
    Дытнерский, стр.239 формула 6.35
    """      
    return m_distrib * (R + 1) / R