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;
vector<char> mn;
vector<int> used;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  used.resize(s.size());
  mn.resize(s.size());
  for (long long i = s.size() - 1; i >= 0; i--) {
    if (i == s.size() - 1) {
      mn[i] = s[i];
    } else {
      mn[i] = min(s[i], mn[i + 1]);
    }
  }
  string ans = "", dop = "";
  for (long long i = 0; i < s.size(); i++) {
    ;
    if (dop.size() > 0 && dop[dop.size() - 1] <= mn[i]) {
      ans += dop[dop.size() - 1];
      dop.erase(dop.size() - 1, 1);
      i--;
      continue;
    }
    if (s[i] == mn[i]) {
      ans += s[i];
    } else {
      dop += s[i];
    }
  }
  if (dop.size() > 0) reverse(dop.begin(), dop.end());
  cout << ans + dop;
  return 0;
}
