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 MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const int MAXN = 1e5 + 5;
char a[MAXN];
char minn[MAXN];
stack<char> s;
int main() {
  scanf("%s", a);
  int m = 1000;
  int len = strlen(a);
  for (int i = len - 1; i >= 0; i--) {
    if (m > a[i]) {
      m = a[i];
    }
    minn[i] = m;
  }
  string ans;
  for (int i = 0; i < len; i++) {
    if (minn[i] == a[i]) {
      ans += a[i];
      while (!s.empty()) {
        if (s.top() <= minn[i + 1]) {
          ans += s.top();
          s.pop();
        } else
          break;
      }
    } else {
      s.push(a[i]);
    }
  }
  while (!s.empty()) {
    ans += s.top();
    s.pop();
  }
  cout << ans << endl;
}
