#include <cstdio>
#include <cstdlib>
#include <algorithm>
#define nx 1000005
using namespace std;
char a[nx];
int b[nx];
int main()
{
	 freopen("ordine.in","r",stdin);
	 freopen("ordine.out","w",stdout);
	 scanf("%s",&a);int i,x=strlen(a);
	 for ( i=0;i<x;++i)
		 b[i]=a[i]-'a';
	 sort(b,b+x);
	 int j=1;
	 for (i=0;i<x;++i)
	 {
		 if (j<=i) j=i+1;
		 for (;j<x&& b[j]==b[i];++j) ;
			swap (b[i+1],b[j]);
	 }
	 char c;
	 for (i=0;i<x;++i)
	 {
		 c=b[i]+'a';
		 printf("%c",c);
	 }
	 return 0;
}