input_file
M19,Q,P,
M31,M19,Pl,
M420,M31,E,
M421,M31,E,
M33,M31,E,
M438,M33,Pl,
M445,M33,E,
M437,M33,E,
M444,M33,E,
M73,M33,E,
M552,M73,Pl,
M553,M73,Pl,
M569,M73,E,
M549,M73,E,
M550,M73,E,