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;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
const ll oo = 1e18;
const ll MOD = 1e9 + 7;
string s, u;
stack<char> t;
map<char, int> indices;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> s;
  int idx = 0;
  for (int i = 0; i < s.size(); i++) indices[s[i]] = i;
  while (idx < s.size()) {
    auto [c, last] = (*indices.begin());
    while (not t.empty() && t.top() <= c) {
      u += t.top();
      t.pop();
    }
    for (; idx <= last; idx++)
      if (s[idx] == c)
        u += s[idx];
      else
        t.push(s[idx]);
    indices.erase(begin(indices));
  }
  while (not t.empty()) {
    u += t.top();
    t.pop();
  }
  cout << u;
}
