import sys
import os
import shutil
fName = sys.argv[1]
i = 0
while os.path.exists( fName + ".bak%d" % i ): i += 1
bakName = fName + ".bak%d" % i
shutil.move( fName, bakName )
r = open(bakName)
w = open(fName, "w" )
for line in r:
line = line[:-1]
while len(line) and (line[-1] == " " or line[-1] == " "):
line = line[:-1]
w.write(line+"\n")
w.close()
r.close()