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;
char M[100000];
void solve() {
  string S;
  cin >> S;
  stack<char> T;
  string U;
  M[S.length() - 1] = S[S.length() - 1];
  for (int i = S.length() - 2; i >= 0; --i) M[i] = min(S[i], M[i + 1]);
  for (unsigned i = 0; i < S.length();) {
    char c = M[i];
    while (i < S.length() && M[i] == c) {
      if (S[i] == c)
        U += c;
      else
        T.push(S[i]);
      i++;
    }
    if (i == S.length()) break;
    while (!T.empty() && T.top() <= M[i]) {
      U += T.top();
      T.pop();
    }
  }
  while (!T.empty()) {
    U += T.top();
    T.pop();
  }
  cout << U;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  solve();
  return 0;
}
