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 + 10;
int f[N], tot = 0;
char a[N], ans[N];
stack<char> s;
int main() {
  scanf("%s", a + 1);
  int n = strlen(a + 1);
  f[n + 1] = 100;
  for (int i = n; i >= 1; i--) {
    f[i] = min(a[i] - '0', f[i + 1]);
  }
  for (int i = 1; i <= n; i++) {
    while (!s.empty()) {
      int x = s.top() - '0';
      if (x <= f[i]) {
        ans[++tot] = s.top();
        s.pop();
      } else
        break;
    }
    if (f[i] == a[i] - '0') {
      ans[++tot] = a[i];
    } else {
      s.push(a[i]);
    }
  }
  while (!s.empty()) {
    ans[++tot] = s.top();
    s.pop();
  }
  puts(ans + 1);
  return 0;
}
