Educational Codeforces Round 19 C

Description

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 lexigraphically 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
题意：第一个字符串的首字母放在第二个字符串的中，第二个字符串的结尾再输出，求能够得到字典序最小的字符串
解法：模拟，如果第一个字符串的首字母为最小，则直接输出，否则压入栈内，处理完毕之后再输出

 #include <bits/stdc++.h>
 using namespace std;
 int num[];
 string s;
 int check(char c)
 {
     for(int i='a';i<c;i++)
     {
         if(num[i])
         {
             return ;
         }
     }
     return ;
 }
 stack<char>q;
 int main() {
     ios::sync_with_stdio(false);
     cin.tie();
     cin>>s;
     for(int i=;i<s.size();i++)
     {
         num[s[i]]++;
     }
     int cnt=;
     while(cnt<s.size())
     {
         if(q.empty())
         {
             q.push(s[cnt]);
             num[s[cnt]]--;
             cnt++;
         }
         else if(check(q.top()))
         {
             cout<<q.top();
             q.pop();
         }
         else
         {
             q.push(s[cnt]);
             num[s[cnt]]--;
             cnt++;
         }
     }
     while(!q.empty())
     {
         cout<<q.top();
         q.pop();
     }
     return ;
 }