#include <fstream>
#include <string.h>
using namespace std;
ifstream f("ordine.in");
ofstream g("ordine.out");
int j,i;
char x[100],aux;
int main()
{
    f>>x;
    for(i=0;i<strlen(x);i++)
        for(j=i+1;j<strlen(x);j++)
                                    if(x[i]>x[j]) {
                                                        aux=x[i];
                                                        x[i]=x[j];
                                                        x[j]=aux;
                                                    }

    for(i=1;i<strlen(x);i++)
                                    if(x[i]==x[i-1]){
                                                        j=i+1;
                                                        while(x[j]==x[i]) j++;
                                                        aux=x[i];
                                                        x[i]=x[j];
                                                        x[j]=aux;
                                                   }
    g<<x<<'\n';

}