In the technique of electron impact mass spectroscopy, molecular fragment are identified through a characteristic pattern of peaks at different values of m/z (ions mass charge ratio - the charge on the ion is usually -1, so the peak position directly corresponds to the mass of the ion). The set of peaks at the maximum m/z is often due to the monoanion created from the intact molecule by electron attachment. Consider the polychlorinated bipyrrole C9H3N2Cl7. Find the nominal mass of the molecule.