#include<stdio.h>
int main(){

FILE *f=fopen("ordine.in","r");
char v[100001];
char t[100001];
long int i,j;
char x;
i=96;

for (i=1;i<=100001;i++){
v[i]=0;
}


 while(!feof(f)){
  i++;
  fscanf(f,"%c",&x);
  v[x]++;
 }

fclose(f);


j=0;

 for(i=97;i<=122;i++){
  while(v[i]!=0){
  j++;t[j]=i;
  v[i]--;
  }
 }

 int i2,aux;

  for(i=1;i<=j;i++){
   i2=i+1;

    if(t[i]==t[i2])
    while(t[i]==t[i2])
    {
    i2++;
    }
   x=t[i+1];
   t[i+1]=t[i2];
   t[i2]=x;

  }

  FILE *g=fopen("ordine.out","w");
  for(i=1;i<=j;i++){
  fprintf(g,"%c",t[i]);
  }

fclose(g);



return 0;
}