Calculator

#python calculator
#steve basford 2015
def add():
    answer = (num1) + (num2)
    print (answer)
def subtract():
    answer = (num1) - (num2)
    print (answer)
def divide():
    if num1 == "0"
    answer = (num1) / (num2)
    print (answer)
def multiply():
    answer = (num1) * (num2)
    print (answer)
print("Welcome to my very first calculator!")
choice = input("(A)ddition (S)ubtraction (D)ivision (M)ultiplication")
num1 = int(input("Enter the first number"))
num2 = int(input("Enter the second number"))
if choice == "a":
    add()
elif choice == "s":
    subtract()
elif choice == "d":
    divide()
elif choice == "m":
    multiply()