z = 1
while z < 2:
    select = input("Enter:\n"
                "+\n"
                "-\n"
                "*\n"
                "/\n"
                "\n")

    if select == "+" or select == "-" or select == "*" or select == "/":
        z += 1

    def addition():
        a = float(input("a = "))
        b = float(input("b = "))
        c = a + b
        print("The sum is: ", c)

    def subtraction():
        a = float(input("a = "))
        b = float(input("b = "))
        c = a - b
        print("The sum is: ", c)

    def multiplication():
        a = float(input("a = "))
        b = float(input("b = "))
        c = a * b
        print("The sum is: ", c)

    def division():
        a = float(input("a = "))
        b = float(input("b = "))
        c = a / b
        print("The sum is: ", c)

    if select == "+":
        addition()
    elif select == "-":
        subtraction()
    elif select == "*":
        multiplication()
    elif select == "/":
        division()