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

using namespace std;

int main() {
	vector<int> v;
	int k = 0;
	
	string s;
	cin >> s;
	while (s != "exit") {
		if (s == "push") {
			int n;
			cin >> n;
			v.push_back(n);
			
			cout << "ok\n";
		} else if (s == "pop") {
			cout << v[k] << "\n";
			k = k + 1;
		} else if (s == "front") {
			cout << v[k] << "\n";
		} else if (s == "size") {
			cout << v.size() - k << "\n";
		} else if (s == "clear") {
			v.clear();
			k = 0;
			cout << "ok\n";
		}
		
		cin >> s;
	}
	cout << "bye\n";
	
	return 0;
}