def calculator(number1, number2, operator):
    if operator == "+":
        return f"result: {number1 + number2}"
    elif operator == "-":
        return f"result: {number1 - number2}"
    elif operator == "*":
        return f"result: {number1 * number2}"
    elif operator == "/":
        if number2 == 0:
            return "Error: Division by zero is not allowed."
        return f"result: {number1 / number2}"
    else:
        return "Error: Invalid operator."

try:
    number1 = int(input("Enter number1: "))
    number2 = int(input("Enter number2: "))
    operator = input("Please enter an operator (+, -, *, /): ").strip()
    print(calculator(number1, number2, operator))
except ValueError:
    print("Error: Please enter valid numbers.")