#include <stdio.h>
#include <string.h>

int n,i,j;
char aux,s[1000000];
int main()
{
    freopen("ordine.in","rt",stdin);
    gets(s);
    n=strlen(s);
    for (i=0;i<n-1;++i)
         for (j=i+1;j<n;++j)
               if (s[i]>s[j])
                    {
                        aux=s[i];
                        s[i]=s[j];
                        s[j]=aux;
                    }
    for (i=1;i<n;++i)
         if (s[i]==s[i-1])
              for (j=i;j<=j;++j)
                   if (s[j]!=s[i])
                       {
                        aux=s[i];
                        s[i]=s[j];
                        s[j]=aux;
                        break;
                        }                 
    freopen("ordine.out","wt",stdout);
    for (i=0;i<n;++i)
          printf("%c", s[i]);
return 0;
}