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 + 6;
char s[N];
char last[N];
int main() {
  scanf("%s", s);
  int n = strlen(s);
  char now = s[n - 1];
  for (int i = n - 1; i >= 0; i--) {
    now = min(s[i], now);
    last[i] = now;
  }
  int i = 0;
  stack<char> st;
  for (int it = 0; it < n; it++) {
    if (i < n) {
      bool ok = 0;
      while (st.empty() || st.top() > last[i]) {
        if (last[i] == s[i]) {
          printf("%c", s[i]);
          ok = 1;
          i++;
          break;
        }
        st.push(s[i]);
        i++;
      }
      if (!ok) {
        printf("%c", st.top());
        st.pop();
      }
    } else {
      printf("%c", st.top());
      st.pop();
    }
  }
  printf("\n");
  return 0;
}
