During a one-hour interval monitored through Cyara CX Assurance, a call center has x agents. y percent of the agents answer exactly one call each. Of the remaining agents, half answer two calls each and the other half answer no calls.
Implement a function that returns the total number of answered calls. Return -1 when the distribution is impossible because the one-call group is not a whole number of agents or the remaining agents cannot be split equally.
Implement calls_answered(x, y), where x is an integer agent count and y is an integer percentage from 0 through 100. Return an integer representing the total calls answered, or -1 for an invalid distribution. Do not use floating-point arithmetic.
def calls_answered(x, y):