def read_confounds(confounds):
    """ Process input list of confounds.

    Parameters
    ----------
    confounds : list of str
        List of confounds with categorical variables indicated by c(var) ('c' must be lower case).

    Returns
    -------
    list
        List of all confounds without wrapper on categorical variables: c(var) -> var.
    list
        List of only categorical confounds without wrapper.
    """
    categorical = []
    clean_confounds = []
    for conf in confounds:
        if ((conf[0:2] == 'c(') & (conf[-1] == ')')):
            categorical.append(conf[2:-1])
            clean_confounds.append(conf[2:-1])
        else:
            clean_confounds.append(conf)
    return clean_confounds, categorical