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 main() {
  string s, t, u;
  cin >> s;
  set<int> idxs;
  int n = s.length(), a[100010], idx_min = n - 1;
  a[n - 1] = n - 1;
  char curr_min = s[n - 1];
  for (int i = n - 2; i >= (int)0; i--) {
    if (curr_min >= s[i]) {
      curr_min = s[i];
      idx_min = i;
    }
    a[i] = idx_min;
  }
  for (int i = 0; i < (int)n; i++) idxs.insert(a[i]);
  bool first = true;
  int curr_idx = 0;
  for (auto r : idxs) {
    if (!first) {
      while (t.size() && s[r] >= t.back()) {
        u += t.back();
        t.pop_back();
      }
    }
    first = false;
    for (int i = curr_idx; i < (int)r; i++) t += s[curr_idx++];
    u += s[curr_idx++];
  }
  for (int i = 0; i < (int)t.length(); i++) u += t[t.length() - 1 - i];
  cout << u << "\n";
}
