#include <iostream>

using namespace std;

struct Qeueue {
    int container_[1000];
    int size_ = 0;
    int start_ = 0;
    
    void push(int n) {
        if (start_ + size_ == 1000) {
            for (int i = 0; i < size_; i++) {
                container_[i] = container_[start_ + i];
            }
            start_ = 0;
        }
        container_[size_ + start_] = n;
        size_++;
    }
    
    int front() {
        return container_[start_];
    }
    
    int pop() {
        int out = front();
        start_++;
        size_--;
        return out;
    }
    
    int size() {
        return size_;
    }
    

    void clear() {
        start_ = 0;
        size_  = 0;
    }
};

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