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>
const int INF = 1e9;
using namespace std;
char s[100100];
char str[100100];
int vis[30];
stack<char> st;
int main() {
  scanf("%s", s);
  int len = strlen(s);
  for (int i = 0; i < len; i++) {
    vis[s[i] - 'a']++;
  }
  int k = 0;
  char f = 'a';
  while (k < len) {
    while (!vis[f - 'a'] && f - 'a' <= 26) f++;
    if (k == 0 || st.empty()) {
      st.push(s[k]);
      vis[s[k] - 'a']--;
      k++;
      continue;
    }
    if (st.top() > f && k < len) {
      st.push(s[k]);
      vis[s[k] - 'a']--;
      k++;
    } else {
      cout << st.top();
      st.pop();
    }
  }
  while (!st.empty()) {
    cout << st.top();
    st.pop();
  }
  cout << endl;
  return 0;
}
