2023.12.17.

# class school:#     def __init__(self, x, y):#         print('This is Initialize Function')#         # self: 클래스 내에서 자유롭게 가져다가 쓸 수 있도록 하는 마법의 단어#         self.x = x#         self.y = y##     def vol(self):#         print('VOL')#         print(self.x + self.y)## a,b = map(int, input().split())## x = school(a, b)# x.vol()'''FILO: First In, Last Outif condition {}else {}List = [0, 0, 0, 0, 0] # stack'''# 입력값에 0 없음# class stack:#     def __init__(self, N):#         self.N = N#         self.list = []#         for i in range(self.N):#             self.list.append(0)#         self.top = -1##     def push(self, x):#         if self.top < self.N -1:#             self.list[self.top+1] = x#             self.top += 1#         else:#             print("범위 넘어감")##     def pop(self):#         if self.top > -1:#             self.list[self.top] = 0#             self.top -= 1#         else:#             print("범위 넘어감")##     def view(self):#         for i in range(self.N):#             if self.list[self.N-1-i] != 0:#                 print(self.list[self.N-1-i])#     def is_empty(self):#         num = 0#         for i in range(self.N):#             if self.list[i] == 0:#                 num += 1#         if num == self.N:#             print('Y')#         else:#             print('N')#     def is_full(self):#         num = 0#         for i in range(self.N):#             if self.list[i] == 0:#                 num += 1#         if num == 0:#             print('Y')#         else:#             print('N')#### n = int(input())# k = stack(n)## # for i in range(n):# while True:#     x = input()#     a1 = -1#     for i in x:#         if i == '(':#             break#         a1 += 1#     if x[a1+2:-1] != '':#         num = int(x[a1+2:-1])##     s = x[:a1+1]#     if s == "push":#         k.push(num)#     elif s == "pop":#         k.pop()#     elif s == "is_empty":#         k.is_empty()#     elif s == "is_full":#         k.is_full()#     elif s == "view":#         k.view()class stack:    def __init__(self):        self.N = 205        self.printlist = []        self.list = []        for i in range(self.N):            self.list.append(1.1)        self.top = -1        self.printnum = 0    def push(self, x):        if self.top < self.N -1:            self.list[self.top+1] = x            self.top += 1    def pop(self):        if self.top > -1:            self.list[self.top] = 0            self.top -= 1    def Top(self):        if self.list[self.top] == 1.1:            self.printlist.append(-1)            self.printnum += 1        else:            self.printlist.append(self.list[self.top])            self.printnum += 1    def size(self):        self.printlist.append(self.top+1)        self.printnum += 1    def empty(self):        if self.top + 1 == 0:            self.printlist.append("true")            self.printnum += 1        else:            self.printlist.append("false")            self.printnum += 1n = int(input())k = stack()for i in range(n):    x = input()    if x.__contains__('push'):        num = int(x[6:-2])        k.push(num)    elif x.__contains__('pop'):        k.pop()    elif x.__contains__('top') == True:        k.Top()    elif x.__contains__('size') == True:        k.size()    elif x.__contains__("empty") == True:        k.empty()for i in range(k.printnum):    print(k.printlist[i])# string = 'Hello World'# print(string.__contains__('Hello'))# string = 'push( 5523423232355 )'# print(string[6:-2])