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 double eps = 1e-4;
const double PI = acos(-1.0);
const int INF = 1e9 + 10;
const int MOD = 1e9 + 7;
const int N = 1e5 + 10;
char s[N], b[N];
int main() {
  while (~scanf("%s", s)) {
    int len = strlen(s);
    b[len - 1] = s[len - 1];
    for (int i = len - 2; i >= 0; i--) b[i] = min(s[i], b[i + 1]);
    b[len] = '\0';
    stack<char> q;
    while (!q.empty()) q.pop();
    for (int i = 0; i < len; i++) {
      q.push(s[i]);
      while (!q.empty() && q.top() <= b[i + 1]) {
        printf("%c", q.top());
        q.pop();
      }
    }
    while (!q.empty()) {
      printf("%c", q.top());
      q.pop();
    }
    puts("");
  }
  return 0;
}
