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;
const int maxn = 1e5 + 5;
char ch[maxn];
char minCh[maxn];
queue<char> res;
stack<char> temp;
int main() {
  scanf("%s", ch);
  int len = strlen(ch);
  for (int i = len - 1; i >= 0; i--) {
    minCh[i] = ch[i];
    if (i < len - 1) minCh[i] = min(minCh[i + 1], minCh[i]);
  }
  for (int i = -1;;) {
    if (i + 1 >= len) break;
    char nx = minCh[i + 1];
    if (temp.size() && temp.top() <= nx) {
      res.push(temp.top());
      temp.pop();
      continue;
    }
    while (ch[++i] != nx) temp.push(ch[i]);
    res.push(nx);
  }
  while (temp.size()) res.push(temp.top()), temp.pop();
  while (res.size()) printf("%c", res.front()), res.pop();
  printf("\n");
  return 0;
}
