def infix(formula: str, arg: int):
    """
    evaluation of infix expression
    :param formula: bytebeat formula
    :param arg:     time argument
    :return: int:
        computation result
    """
    characters = formula.replace("t", str(arg)).replace("/", "//")
    try:
        return eval(characters)
    except ZeroDivisionError:
        return 0