glob, sorting file names

#!/usr/bin/env python

import glob, os

YEAR = "2019"

def cmpr( x, y):
    #
    # x: Meeting20190508.tex  
    #
    m1 = x[11:13] # 05
    d1 = x[13:15] # 08
    m2 = y[11:13]  
    d2 = y[13:15] 
    z1 = int( m1) * 31 + int(d1) 
    z2 = int( m2) * 31 + int(d2)
    return cmp( z1, z2)
    
def main():
    files = glob.glob( 'Meeting%s*.tex' % YEAR)
    files.sort( cmpr)
    for f in files:
        print( "File %s" % f)
        os.system( "cat %s >> Meetings%s.tex" % (f, YEAR))
    return

if __name__ == "__main__":
    main()