Untitled

class Node:
    def __init__(self, info=None):
        self.info = info
        self.next = None


class Stack:
    def __init__(self):
        self.first = Node()

    def isEmpty(self):
        return self.first.next is None

    def push(self, info):
        new_node = Node(info)
        new_node.next = self.first.next
        self.first.next = new_node

    def pop(self):
        popped_node = self.first.next
        self.first.next = popped_node.next
        return popped_node.info

    def top(self):
        return self.first.next.info


def Check(string):
    string = Stack()
    for chr in string:
        if chr in {'[','(','{'}:
            string.push(chr)
        else:
            if chr in {']',')','}'}:
                if string.isEmpty():
                    return False


def main():
    mystack = Stack()
    mystack.push(5)
    print(mystack.top())
    print(mystack.pop())
    print(mystack.isEmpty())
main()