/*
 Author: 曹北健
 Result: AC Submission_id: 4351478
 Created at: Tue Apr 19 2022 22:56:42 GMT+0800 (China Standard Time)
 Problem_id: 236    Time: 2 Memory: 1732
*/

#include <stdio.h>
#include <string.h>
int main(){
    char s[128] = { 0 }, tmp;
    int i, j, n;
    while(scanf("%s",s)!=EOF){
        n = strlen(s);
        for(i = 0; i < n; i++){
            for(j = i + 1; j < n; j++){
                if(s[i] > s[j]){
                    tmp = s[i]; s[i] = s[j]; s[j] = tmp;
                }
            }
        }
        printf("%s\n", s);
    }
    return 0;
}