2_D

#include <cmath>
#include <iostream>
#include <vector>
#include <queue>
#include <deque>
#include <string>

using std::cin;
using std::cout;
using std::max;
using std::min;
using std::string;
using std::vector;
using std::queue;
using std::deque;
//sample-потестить: как добавлять и удалать из deque mini
int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);
  std::cout.tie(0);
  queue<int> qu;
  deque<int> mini;
  int req;
  cin >> req;
  int cnt = 0;
  for (int go = 0; go < req; ++go) {
    string ask;
    cin >> ask;
    if (ask == "enqueue") {
      cnt++;
      int nmb; cin >> nmb;
      qu.push(nmb);
      cout << "ok\n";
      while (!mini.empty() && mini.back() > nmb) {
        mini.pop_back();
      }
      mini.push_back(nmb);
    } else if (ask == "dequeue") {
      if (qu.empty()) {
        cout << "error\n";
        continue;
      }
      cout << qu.front() << "\n";
      if (mini.front() == qu.front()) {
        mini.pop_front();
      }
      qu.pop();
      cnt--;
    } else if (ask == "front") {
      if (qu.empty()) {
        cout << "error\n";
        continue;
      }
      cout << qu.front() << "\n";
    } else if (ask == "size") {
      cout << cnt << "\n";
    } else if (ask == "clear") {
      while (!qu.empty()) {
        qu.pop();
      }
      while (!mini.empty()) {
        mini.pop_back();
      }
      cnt = 0;
    } else if (ask == "min") {
      if (cnt == 0) {
        cout << "error\n";
        continue;
      }
      cout << mini.front() << "\n";
    }
  }
}