12770

#include <iostream>

#include <string>
#include <string.h>
#include <map>

using namespace std;

map<char,int> mp;
int main()
{
string str;

while(cin>>str)
{
if(str=="#")
break;

mp.clear();
for(int i=0;i<str.size();i++)
{
mp[str[i]]+=1;
}

if(mp.size()==1)
{
cout<<"\n";
continue;
}

int k=0;
map<char,int> m;
for(map<char,int>::iterator i=mp.begin();i!=mp.end();++i)
{
if((i->second)%2!=0)
{
k++;
m[i->first]=1;
}
}

int s=0;
for(map<char,int>::iterator i=m.begin();i!=m.end();++i)
{
if(s==k-1)
break;
s++;
cout<<i->first;
}

cout<<"\n";
}

return 0;
}