#include <iostream>
#include <string>
using namespace std;
int main()
{
int C;
cin>>C;
while(C--)
{
string str;
cin>>str;
int p,q,N,C=0,element=0;
N=str.length();
for(p=0;p<N;p++)
{
C=0;
for(q=0;q<N;q++)
{
if(str[q]==str[p])
{
C++;
}
}
if(C>1)
{
element=str[p];
break;
}
}
if(C==0 || element==0)
cout<<".\n";
else
cout<<(char)element<<"\n";
}
return 0;
}
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