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;
string s, u;
stack<char> t;
vector<char> mins;
int main() {
  cin >> s;
  u = "";
  int inicio = 0, tam = s.length();
  char ant = 'z' + 1;
  for (int i = tam - 1; i >= 0; i--) {
    ant = min(ant, s[i]);
    mins.push_back(ant);
  }
  reverse(mins.begin(), mins.end());
  while (inicio < tam) {
    if (t.empty()) {
      t.push(s[inicio]);
      inicio++;
    } else {
      if (t.top() <= mins[inicio]) {
        u += t.top();
        t.pop();
      } else {
        t.push(s[inicio]);
        inicio++;
      }
    }
  }
  while (!t.empty()) {
    u += t.top();
    t.pop();
  }
  if (inicio < tam) {
    u += s[inicio];
  }
  cout << u << "\n";
}
