Petya recieved a gift of a string s with length up to 105 characters for his birthday. He took two more empty strings t and u and decided to play a game. This game has two possible moves:

  * Extract the first character of s and append t with this character. 
  * Extract the last character of t and append u with this character. 



Petya wants to get strings s and t empty and string u lexicographically minimal.

You should write a program that will help Petya win the game.

Input

First line contains non-empty string s (1 ≤ |s| ≤ 105), consisting of lowercase English letters.

Output

Print resulting string u.

Examples

Input

cab


Output

abc


Input

acdb


Output

abdc
#include <bits/stdc++.h>
using namespace std;
int getMass(char atom) {
  if (atom == 'H') return 1;
  if (atom == 'C') return 12;
  if (atom == 'O') return 16;
  return 0;
}
int32_t main() {
  int t = 1;
  while (t--) {
    string expression;
    cin >> expression;
    stack<char> t;
    vector<char> u;
    int len = expression.length();
    vector<char> alphabet(len);
    alphabet[len - 1] = 'z';
    for (int i = len - 2; i >= 0; i--) {
      alphabet[i] = min(expression[i + 1], alphabet[i + 1]);
    }
    for (int i = 0; i < expression.length(); i++) {
      t.push(expression[i]);
      while (!t.empty() && t.top() <= alphabet[i]) {
        u.push_back(t.top());
        t.pop();
      }
    }
    while (!t.empty()) {
      u.push_back(t.top());
      t.pop();
    }
    for (int i = 0; i < u.size(); i++) cout << u[i];
    cout << '\n';
  }
}
