Minimal string 栈 贪心

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<sstream>
#include<algorithm>
#include<queue>
#include<deque>
#include<iomanip>
#include<vector>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<fstream>
#include<memory>
#include<list>
#include<string>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define MAXN 100009
#define N 40
#define MOD 10000007
#define INF 1000000009
const double eps = 1e-;
const double PI = acos(-1.0);
/*
从前往后遍历
要让字典序的顺序尽量小，那么如果该字符后面有字典序比它小的，应当一直压栈直到栈顶元素优先级更高为止。（保证字典序小的优先！）
*/
char s[MAXN],best[MAXN];
stack<char> S;
int main()
{
    scanf("%s", s);
    int l = strlen(s);
    best[l] = 'z';
    int p = ;
    for (int i = l - ; i >= ; i--)
        best[i] = min(s[i], best[i + ]);
    while (!S.empty() || p < l)
    {
        if (!S.empty() && S.top() <= best[p])
            putchar(S.top()), S.pop();
        else
            S.push(s[p++]);
    }
    printf("\n");
    return ;
}