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Problem Statement

You are given a string $S$. Find the lexicographically smallest string $S'$ obtained by permuting the characters of $S$.

Here, for different two strings $s = s_1 s_2 \ldots s_n$ and $t = t_1 t_2 \ldots t_m$, $s \lt t$ holds lexicographically when one of the conditions below is satisfied.

• There is an integer $i\ (1 \leq i \leq \min(n,m))$ such that $s_i \lt t_i$ and $s_j=t_j$ for all integers $j\ (1 \leq j \lt i)$.
• $s_i = t_i$ for all integers $i\ (1 \leq i \leq \min(n,m))$, and $n \lt m$.

Constraints

• $S$ is a string of length between $1$ and $2 \times 10^5$ (inclusive) consisting of lowercase English letters.

Sample Input 1

aba

Sample Output 1

aab

Three strings can be obtained by permuting aba:

• aba
• aab
• baa

The lexicographically smallest among them is aab.

Sample Input 2

zzzz

Sample Output 2

zzzz