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;
using ll = long long;
using pii = pair<int, int>;
void solve() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  string str;
  cin >> str;
  stack<char> st;
  vector<char> prefix(str.size());
  prefix[str.size() - 1] = str[str.size() - 1];
  for (int i = str.size() - 2; i >= 0; i--)
    prefix[i] = min(prefix[i + 1], str[i]);
  vector<char> result;
  int l = 0;
  while (l < str.size()) {
    if (st.empty()) {
      st.push(str[l++]);
    }
    if (l == str.size()) break;
    if (st.top() <= prefix[l]) {
      result.push_back(st.top());
      st.pop();
    } else {
      while (l < str.size() && st.top() > prefix[l]) {
        st.push(str[l++]);
      }
    }
  }
  while (!st.empty()) {
    result.push_back(st.top());
    st.pop();
  }
  for (char c : result) cout << c;
}
int main() {
  solve();
  return 0;
}
