sem4_1

import sys


class ExtendedList(list):
    def get_reversed(self):
        return list(reversed(self))

    reversed = R = property(get_reversed)

    def get_first(self):
        return self[0]

    def set_first(self, x):
        self[0] = x

    first = F = property(get_first, set_first)

    def get_last(self):
        return list(reversed(self))[0]

    def set_last(self, x):
        self[len(self) - 1] = x

    last = L = property(get_last, set_last)

    def get_size(self):
        return len(self)

    def set_size(self, x):
        if x > len(self):
            for i in range(x-len(self)):
                self.append(None)
        elif x < len(self):
            for i in range(len(self) - x):
                self.pop()

    size = S = property(get_size, set_size)


exec(sys.stdin.read())