#include <stdio.h>      
#include <string.h>      
     
int n,i,j;      
char aux,s[100000];
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-1;j<=n;++j)
           if (s[j]!=s[i])   
               {   
            aux=s[i];   
            s[i]=s[j];   
            s[j]=aux;   
            break;   
            }   
    freopen("ordine.out","wt",stdout);   
   i=0;
   while(s[i]>='a' && s[i]<='z')
   {
	   printf("%c",s[i]);
i++;
   }
  
return 0;      
}