#include <iostream>
using namespace std;

struct Element {
	int value;
	Element* next = 0;
};

struct Queue {
	Element* front = 0;
	Element* back = 0;
	int queue_size = 0;
	
	void push(int n) {
		Element* new_elem = new Element();
		new_elem->value = n;
		if (queue_size > 0) {
			back->next = new_elem;
		} else {
			front = new_elem;
		}
		back = new_elem;
		queue_size++;
	}
	
	int pop() {
		int result = front->value;
		Element* old_front = front;
		if (queue_size > 1) {
			front = front->next;
		} else {
			front = 0;
			back = 0;
		}
		delete old_front;
		queue_size--;
		return result;
	}
	
	int top() {
		return front->value;
	}
	
	int size() {
		return queue_size;
	}
	
	void clear() {
		while (size() > 0) {
			pop();
		}
	}
};

int main() {
	Queue q;
	
	string s;
	cin >> s;
	while (s != "exit") {
		if (s == "push") {
			int n;
			cin >> n;
			q.push(n);
			cout << "ok\n";
		} else if (s == "pop") {
			cout << q.pop() << "\n";
		} else if (s == "front") {
			cout << q.top() << "\n";
		} else if (s == "size") {
			cout << q.size() << "\n";
		} else if (s == "clear") {
			q.clear();
			cout << "ok\n";
		}
		
		cin >> s;
	}
	cout << "bye\n";
	return 0;
}