print("Simple python calculator (Task 2)")
print("Choose what to do:")
print("1-Add")
print("2-Subtract")
print("3-Multiply")
print("4-Divide")

transaction = input("Enter transaction(1/2/3/4):") #asking user to choose transaction number

if transaction not in ('1', '2', '3', '4'): #if user's choice is not between transactions 1-4 print "invalid"
    print("Invalid input")

 #else user's choice is between transactions 1-4 then ask num1 and num2

else:
    num1 = int(input("Enter 1st number: "))
    num2 = int(input("Enter 2nd number: "))

#here are the variables of calculation due to user's choice
    getsum = num1 + num2
    subtract = num1 - num2
    multiply = num1 * num2
    divide = num1 / num2

    if transaction == '1' or transaction == '+':
        print(getsum)

    elif transaction == '2' or transaction == '-':
        print(subtract)

    elif transaction == '3' or transaction == '*':
        print(multiply)

    elif transaction == '4' or transaction == '/':
        print(divide)