imagine twin brother sister have person look exactly like unusual its hard having alter ego good bad and twin know likeNow let imagine typical morning family you have not wake Mom go work she hasty nearly forget leave darling child money buy lunch school cafeteria she fish purse find number coin exact n coin arbitrary value a1a2an but Mom run time do not split coin so scribble note ask split money equallyAs wake find Moms coin read note but split money equally think after twin sleeping will not know so decide act like pick subset coin sum value coin strictly large sum value remain coin twin however correctly think coin twin suspect deception so you ve decide stick follow strategy avoid suspicion minimum number coin sum value strictly sum value remain coin on basis determine minimum number coin need divide describe manner