#include<fstream>
using namespace std;
int main()
{ifstream q("ordine.in");
ofstream w("ordine.out");
long a[26]={0},n=0,i,x,y;
char c,z;
q>>c;
while(!q.eof())
   {a[c-97]++;
   n++;
   q>>c;}
c='.';
while(n)
   {y=1;
   for(i=0;i<26;i++)
     {if(a[i]!=0&&char(97+i)!=c&&y)
      {x=i;
      z=char(97+i);
      y=0;}
    if(a[i]>=(n/2+1))
     {x=i;
     z=char(97+i);
     break;}}
   if(z!=c)
    {w<<z;
     n--;
     c=z;
     a[x]--;}}
return 0;}