#include<cstdio>
#include<cstring>
int i,n,x[27],t,j,k;
char s[1000002],o;
int main()
{FILE *f=fopen("ordine.in","r"),*g=fopen("ordine.out","w");
fgets(s,1000002,f);
n=strlen(s)-1;
for(i=0;i<n;i++)
     x[s[i]-'a']++;
for(i=0;i<26;i++)
for(j=0;j<x[i];j++)
     s[k++]=i+'a';
for(i=0;i<n;i++)
     {for(k=-1,j=0;j<26;j++)
     if(x[j]>(n-i)/2)
           k=j;
     if(k>-1)
           {t=i-1;
           if(s[i]!=k+'a')
                t+=x[k];
           o=s[i],s[i]=s[t],s[t]=o,x[k]--;}
     else
           {t=i;
           if(i)
                 t+=x[s[i-1]-'a'];
           o=s[i],s[i]=s[t],s[t]=o,x[s[i]-'a']--;}}
fputs(s,g);  
return 0;}