Queue

#include <bits/stdc++.h>
using namespace std;
const int SIZE = 101;
int que[SIZE] = {};
int head, tail;

void push(int x)
{
  que[head] = x;
  head = (head + 1) % SIZE;
}

void pop()
{
  tail = (tail + 1) % SIZE;
}

int front()
{
  return que[tail];
}

int size()
{
  return (head + SIZE - tail) % SIZE;
}

void clear()
{
  head = tail = 0;
}

int main()
{
  string command;
  while(1)
  {
    cin >> command;
    if (command == "exit") break;
    if (command == "pop")
    {
      cout << front();
      pop();
    }
    else if (command == "front")
    {
      cout << front();
    }
    else if (command == "size")
    {
      cout << size();
    }
    else if (command == "clear")
    {
      clear();
      cout << "ok";
    }
    else if (command == "push")
    {
      int x;
      cin >> x;
      push(x);
      cout << "ok";
    }
    cout << endl;
  }
  cout << "bye";
}