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 maxn = 1e6 + 5;
const int INF = 0x3f3f3f3f;
char s[maxn];
queue<int> q;
int a[maxn];
int main() {
  gets(s);
  int len = strlen(s);
  memset(a, INF, sizeof(a));
  for (int i = len - 1; i >= 0; i--) {
    int k = s[i] - 'a';
    a[i] = min(k, a[i + 1]);
  }
  string ans = "";
  stack<char> st;
  for (int i = 0; i < len; i++) {
    while (!st.empty() && st.top() - 'a' <= a[i]) {
      printf("%c", st.top());
      st.pop();
    }
    st.push(s[i]);
  }
  while (!st.empty()) {
    printf("%c", st.top());
    st.pop();
  }
}
