Identify M and N in the following reaction.Copper glance →Controlled heating in presence of airM+SO2,  M + N →SO2 + Cu

Cu2S→AirCu2O+Cu2S +SO2  Cu2O+Cu2S→ Cu+SO2                         Air blasting is restarted for partial roasting before self reduction, until two-thirds of Cu2S is converted into Cu2O.after this, only heating is continued for the self reduction.