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;
long long MOD = pow(10, 9) + 7;
long long INF = 1ll << 60;
int main() {
  stack<char> s;
  queue<char> q;
  vector<char> ans;
  string sd;
  cin >> sd;
  long long n = sd.length();
  for (long long i = 0; i < n; i++) {
    q.push(sd[i]);
  }
  stack<char> forw;
  char aage[n];
  char cur = 'z';
  aage[n - 1] = sd[n - 1];
  for (long long i = n - 1 - 1; i >= 0; i--) {
    aage[i] = min(sd[i], aage[i + 1]);
  }
  for (long long i = 0; i < n; i++) {
    while (!s.empty() && s.top() <= aage[i]) ans.push_back(s.top()), s.pop();
    if (q.front() == aage[i])
      ans.push_back(q.front());
    else
      s.push(q.front());
    q.pop();
  }
  while (!s.empty()) ans.push_back(s.top()), s.pop();
  for (long long i = 0; i < n; i++) cout << ans[i];
}
