#include<iostream>
#include<cmath>
using namespace std;
class Node
{
	int info;
	Node* link;
public:
	Node(int n = 0, Node* p = NULL)
	{
		info = n;
		link = p;
	}
	friend class list;
};
class list
{
private:
	Node* first; //链表头指针
public:
	list()//构造函数
	{
		first = new Node(0);
	}
	Node* CreatNode(int data)//建立新节点
	{
		Node* P = new Node(data);
		return P;
	}
	void Insert(Node* p)//将p插入生成链表
	{
		Node* tempP = first->link, * tempQ = first;//tempQ指向tempP前面的一个节点
		while (tempP != NULL)
		{
			tempQ = tempP;

			tempP = tempP->link;
		}
		p->link = tempP; //插入节点
		tempQ->link = p;
		first->info++;
	}
	void MakeEmpty()//清空一个链表
	{
		Node* tempP;
		while (first->link != NULL)
		{
			tempP = first->link;
			first->link = tempP->link;
			delete tempP;
			first->info--;
		}
	}
	void PrintList()
	{
			cout << first->info << " Nodes:";
			Node* tempP = first->link;
			while (tempP != NULL)
			{
				cout << tempP->info << " ";
				tempP = tempP->link;
			}
			cout << endl;
	}
	

	void DeleteNode(Node* p)
	{
		Node* tempP = first->link, * tempQ = first;
		while (tempP != NULL && tempP != p)
		{
			tempQ = tempP;
			tempP = tempP->link;
		}
		if (tempP == p)
		{
			tempQ->link = tempP->link;
			delete p;
			first->info--;
		}
	}

	void Not()
	{
		Node* tempP = first;
		Node* tempQ = first->link;
		Node* tempR = first->link->link;
		while (tempR != NULL)
		{
			if (tempQ->info == 4)
			{
				if (tempR->info == 1)
					tempR->info = 0;
				else if(tempR->info == 0)
					tempR->info = 1;
				DeleteNode(tempQ);
				tempQ = tempP->link;
			}
			tempQ = tempR;
			tempR = tempQ->link;
		}

	}

	void And()
	{
		Node* tempP = first->link;
		Node* tempQ = first->link->link;
		Node* tempR = tempQ->link;
		while (tempR != NULL)
		{
			if (tempQ->info == 3)
			{
				if (tempP->info == 1 && tempR->info == 1)
				{
					tempP->info = 1;
					DeleteNode(tempQ);
					DeleteNode(tempR);
					tempQ = tempP->link;
					if (tempQ == NULL)
						tempR = NULL;
					else
						tempR = tempQ->link;
				}
				else
				{
					tempP->info = 0;
					DeleteNode(tempQ);
					DeleteNode(tempR);
					tempQ = tempP->link;
					if (tempQ == NULL)
						tempR = NULL;
					else
						tempR = tempQ->link;
				}
			}
			if (tempR != NULL)
			{
				tempQ = tempQ->link;
				tempP = tempP->link;
				tempR = tempR->link;
			}
			else
			{
				break;
			}
		}
	}

	void Or()
	{
		Node* tempP = first->link;
		Node* tempQ = first->link->link;
		Node* tempR = tempQ->link;
		while (tempR != NULL)
		{
			if (tempQ->info == 2)
			{
				if (tempP->info == 1 ||tempR->info == 1)
				{
					tempP->info = 1;
					DeleteNode(tempQ);
					DeleteNode(tempR);
					if (tempP->link != NULL)
					{
						tempQ = tempP->link;
						tempR = tempQ->link;
					}
					else
					{
						tempQ = NULL;
						tempR = NULL;
					}
				}
				else
				{
					tempP->info = 0;
					DeleteNode(tempQ);
					DeleteNode(tempR);
					if (tempP->link != NULL)
					{
						tempQ = tempP->link;
						tempR = tempQ->link;
					}
					else
					{
						tempQ = NULL;
						tempR = NULL;
					}
				}
			}
			if (tempR != NULL)
			{
				tempQ = tempQ->link;
				tempP = tempP->link;
				tempR = tempR->link;
			}
			else
			{
				break;
			}
		}
	}

	void Print()
	{
		if (first->info > 1)
			cout << "error";
		else
		{
			if (first->link->info == 1)
				cout << "true";
			else
				cout << "false";
		}
	}

	~list()//析构函数，删除所有结点
	{
		MakeEmpty();
		delete first;
	}
};

int main()
{
	list l;
	string temp[255];
	int size = 0;//字符数减一
	while (cin >> temp[size])
	{
		int symble = 0;
		if (cin.get() == '\n')
			symble = 1;
		if (temp[size] == "or")
		{
			l.Insert(l.CreatNode(2));
		}
		else if (temp[size] == "and")
		{
			l.Insert(l.CreatNode(3));
		}
		else if (temp[size] == "not")
		{
			l.Insert(l.CreatNode(4));
		}
		else if (temp[size] == "false")
		{
				l.Insert(l.CreatNode(0));
		}
		else if (temp[size] == "true")
		{
			l.Insert(l.CreatNode(1));
		}
		//cout << size << ":";
		//l.PrintList();
		size++;
		if (symble)
			break;
	}
	//cout << "总：";
	//l.PrintList();

	//cout << "Not:";
	l.Not();
	//l.PrintList();

	//cout << "And:";
	l.And();
	//l.PrintList();

	//cout << "Or:";
	l.Or();
	//l.PrintList();

	l.Print();
}