# -*- coding: iso-8859-1 -*-
#calcutron.py
#def-osio
def add(eka,toka):
    v = eka + toka
    return v
def subtract(eka,toka):
    v = eka - toka
    return v
def multiply(eka,toka):
    v = eka * toka
    return v
def divide(eka,toka):
    if toka != 0:
        v = eka / toka
        return v
    else:
        return "Cannot divide by zero."

#pääohjelma
def main():
    print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
    kysymys = str(raw_input("Give an operation: "))
    while kysymys != "q":
        if kysymys == "a":
            eka = float(raw_input("First number: "))
            toka = float(raw_input("Second number: "))
            vast = add(eka,toka)
            print vast
            print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
            kysymys = str(raw_input("Give an operation: "))
        elif kysymys == "s":
            eka = float(raw_input("First number: "))
            toka = float(raw_input("Second number: "))
            vast = subtract(eka,toka)
            print vast
            print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
            kysymys = str(raw_input("Give an operation: "))
        elif kysymys == "m":
            eka = float(raw_input("First number: "))
            toka = float(raw_input("Second number: "))
            vast = multiply(eka,toka)
            print vast
            print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
            kysymys = str(raw_input("Give an operation: "))
        elif kysymys == "d":
            eka = float(raw_input("First number: "))
            toka = float(raw_input("Second number: "))
            if toka != 0:
                vast = divide(eka,toka)
                print vast
                print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
                kysymys = str(raw_input("Give an operation: "))
            else:
                print "Cannot divide by zero."
                print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
                kysymys = str(raw_input("Give an operation: "))
        elif kysymys != ("a","s","m","d","q"):
            print "WHAT ARE YOU DOING?"
            print "(a)dd, (s)ubtract, (m)ultiply, (d)ivide, (q)uit"
            kysymys = str(raw_input("Give an operation: "))
        else:
            break
if __name__ == '__main__':
    main()