class TendonWalk:

    def __init__(self):
        self.place = 0
        self.distance = 0

    def ten(self):
        self.place += 2
        self.distance += 2

    def don(self):
        self.place -= 1
        self.distance +=1
    
    def derive(self, x):
        while True:
            if x == self.place:
                return self.distance
            self.ten()
            if x == self.place:
                return self.distance
            self.ten()
            if x == self.place:
                return self.distance
            self.don()
            if x == self.place:
                return self.distance
            self.don()
            if x == self.place:
                return self.distance
            self.ten()
            if x == self.place:
                return self.distance
            self.don()
            if x == self.place:
                return self.distance
            self.don()
            if x == self.place:
                return self.distance

tendon_walk = TendonWalk()
tendon_walk.derive(X)