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;
string solve(char *s, int len);
int main() {
  char s[100005];
  int len;
  cin >> s;
  len = strlen(s);
  cout << solve(s, len) << endl;
  return 0;
}
string solve(char *s, int len) {
  char *minimum = new char[len + 1];
  minimum[len] = 'z' + 1;
  for (int i = len - 1; i >= 0; i--) {
    minimum[i] = min(minimum[i + 1], s[i]);
  }
  stack<char> stk;
  char top;
  string ans;
  int j = 0;
  while (j < len) {
    while (!stk.empty() && stk.top() <= minimum[j]) {
      ans += stk.top();
      stk.pop();
    }
    stk.push(s[j]);
    j++;
  }
  while (!stk.empty()) {
    ans += stk.top();
    stk.pop();
  }
  return ans;
}
