#include <iostream>
#include <vector>
#include <string>

using namespace std;

struct MyQueue {
	vector<int> v;
	int k = 0;

	void push(int n) {
		v.push_back(n);
	}
	
	int front() {
		return v[k];	
	}
	
	int pop() {
		k = k + 1;
		return v[k - 1];
	}
	
	int size() {
		return v.size() - k;
	}
	
	void clear() {
		v.clear();
		k = 0;
	}
};

int main() {
	MyQueue 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.front() << "\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;
}