Calculator

Write a program that do basic calculations.

You need to be able to get basic operators such as +, - , *, /, % (modulo) and ^ (Exponentiation). Input will be integer numbers.

Your program will give a usage message if you don't give the three parameters.

For every other errors like if an operand is not an integer, you'll print an input error.

Examples

oa@localhost$ ./solution.py 1 + 1
2
oa@localhost$ ./solution.py
usage: ./solution.py a_number (an_operator +-*/%^) a_number
oa@localhost$ ./solution.py 1 / 0
input error
oa@localhost$

Advices

On Mac and Linux (shell), to input an asterix to a python script you must type \* or "*", such as:

mbp|110-$ python solution.py 3 / 5
0.6
mbp|110-$ python solution.py 3 + 5
8
mbp|110-$ python solution.py 3 - 5
-2
mbp|110-$ python solution.py 3 * 5
usage: python3 ./solution.py a_number (an_operator +-*/%^) a_number
mbp|110-$ python solution.py 3 \* 5
15

Similarly, on Windows with Command Prompt, ^ must be passed with double quotes: "^".