def docalculation():
    entrada = input("press 1 to odd, 2 for substracting, 3 for divide, 4 for multiply or 5 for average numbers> ")
    if entrada == "":
        print("Bye.")
    elif entrada.isdigit():
        input1 = input("write the firt number ")
        input2 = input("write the secound number ")
        number1 = int(input1)
        number2 = int(input2)
        result = 0
        output = str(result)
        if int(entrada) == 1 or int(entrada) == 2 or int(entrada) == 3 or int(entrada) == 4 or int(entrada) == 5:
            if entrada == 1:
                result = number1+number2
            elif entrada ==2:
                result = input1-input2
            elif entrada == 3:
                result == input1/input2
            elif entrada == 4:
                result = input1*input2
            elif entrada == 5:
                how_many = int(input("how many numbers? "))
                how_many = int(how_many)
                total = 0
                for count_numbers in range(how_many):
                    number = input("enter number " + str(count_numbers) + ">")
                    total = total+int(number)
                result= total/how_many
        print(str(number1) + " + " + str(number2) + "=" + output)
    else:
        print("please enter a valid number. ")
docalculation()