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 N = 100111;
stack<char> stk;
char a[N], s[N];
string otp = "";
char maxx = 'z' + 2;
int main() {
  scanf("%s", s);
  int len = strlen(s);
  for (int i = len - 1; i >= 0; --i) {
    maxx = min(maxx, s[i]);
    a[i] = maxx;
  }
  for (int i = 0; i < len; ++i) {
    while (!stk.empty() && stk.top() <= a[i]) {
      otp += stk.top();
      stk.pop();
    }
    stk.push(s[i]);
  }
  while (!stk.empty()) {
    otp += stk.top();
    stk.pop();
  }
  cout << otp << "\n";
  return 0;
}
