#!/usr/bin/python3

import sys  # (1) import
#print(sys.argv)
#print(len(sys.argv))

# let's say we wanted to run the program
#  ./args.py 3 +
# (2) make sure enough arguments, if not print usage statement
if len(sys.argv) < 4 or sys.argv[2] != '+':
    print("Usage: ./args.py n1 + n2")
    sys.exit()

# (3) use sys.argv[whatever], convert if needed
n1 = int(sys.argv[1])
n2 = int(sys.argv[3])

print(n1, '+', n2, '=', n1+n2)