set_reserve = set(reserve)-set(lost) set_lost = set(lost) - set(reserve)
def solution(n, lost, reserve): set_reserve = set(reserve) - set(lost) set_lost = set(lost)-set(reserve) for i in set_reserve: if i-1 in set_lost: set_lost.remove(i-1) elif i+1 in set_lost: set_lost.remove(i+1) return n-len(set_lost)