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 = 1e5 + 5;
int n;
char str[N];
char suf[N];
int ptr;
stack<char> s;
int main() {
  scanf("%s", str + 1);
  n = strlen(str + 1);
  suf[n] = str[n];
  for (int i = n - 1; i >= 1; --i) {
    suf[i] = min(str[i], suf[i + 1]);
  }
  ptr = 1;
  while (!s.empty()) {
    s.pop();
  }
  for (int i = 1; i <= n; ++i) {
    if (ptr > n) {
      printf("%c", s.top());
      s.pop();
    } else if (!s.empty() && s.top() <= suf[ptr]) {
      printf("%c", s.top());
      s.pop();
    } else {
      while (ptr <= n && str[ptr] != suf[ptr]) {
        s.push(str[ptr++]);
      }
      s.push(str[ptr++]);
      printf("%c", s.top());
      s.pop();
    }
  }
  printf("\n");
}
