#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<=n;++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;   
}