diff --git a/exercises/week5/series/sources-solution/main.py b/exercises/week5/series/sources-solution/main.py
index c67e12f..4fa51d4 100644
--- a/exercises/week5/series/sources-solution/main.py
+++ b/exercises/week5/series/sources-solution/main.py
@@ -1,55 +1,63 @@
 ################################################################
 from __future__ import print_function
 import sys
+import argparse
 from compute_pi import ComputePi
 from compute_arithmetic import ComputeArithmetic
 from print_series import PrintSeries
 from plot_series import PlotSeries
 ################################################################
 
 
 def main():
 
-    argc = len(sys.argv)
-    if argc < 5:
-        print('Usage: python3 main.py series_type dumper_type maxiter freq\n\n'
-              '\tseries_type: pi/arithmetic\n'
-              '\tdumper_type: print/plot\n'
-              '\tmaxiter: number of loop iteration to compute the series\n'
-              '\tfreq: frequency at which dumps/plots are made\n\n')
-        sys.exit(-1)
-
-    series_type = sys.argv[1]
-    dumper_type = sys.argv[2]
-    maxiter = int(sys.argv[3])
-    freq = int(sys.argv[4])
-
-    outfile = ""
-    if argc == 6:
-        outfile = sys.argv[5]
-
+    parser = argparse.ArgumentParser(
+        description='Series exercise in python')
+    parser.add_argument('-s', '--series_type', type=str,
+                        help=('pi or arithmetic'),
+                        required=True)
+    parser.add_argument('-d', '--dumper_type', type=str,
+                        help=('print or plot'),
+                        required=True)
+    parser.add_argument('-n', '--maxiter', type=int, required=True,
+                        help='number of loop iteration to compute the series')
+    parser.add_argument('-f', '--frequency', type=int, default=1,
+                        help='frequency at which dumps/plots are made')
+    parser.add_argument('-o', '--outfile', type=str, default="",
+                        help='file where to store the output')
+
+    args = parser.parse_args()
+    series_type = args.series_type
+    dumper_type = args.dumper_type
+    maxiter = args.maxiter
+    freq = args.frequency
+    outfile = args.outfile
+
+    # creation of ojects
     if series_type == "pi":
         serie_object = ComputePi()
     elif series_type == "arithmetic":
         serie_object = ComputeArithmetic()
     else:
         raise RuntimeError("unknown series type: " + series_type)
 
     if dumper_type == "print":
         dumper_object = PrintSeries(serie_object, maxiter, freq)
     elif dumper_type == "plot":
         dumper_object = PlotSeries(serie_object, maxiter, freq)
     else:
         print("unknown dumper type: " + dumper_type)
         sys.exit(-1)
 
     dumper_object.setPrecision(20)
 
+    # start of the run
     if outfile != "":
         _file = open(outfile, 'w')
         _file.write(str(dumper_object))
     else:
         print(dumper_object)
 
 
-main()
+if __name__ == "__main__":
+    main()
diff --git a/exercises/week5/series/sujet.pdf b/exercises/week5/series/sujet.pdf
index 4470262..a9744de 100644
Binary files a/exercises/week5/series/sujet.pdf and b/exercises/week5/series/sujet.pdf differ