#include <bits/stdc++.h>
using namespace std;
int main()
{
int t;
cin>>t;
while(t--)
{
string x;
cin>>x;
int s,c=0,w=0;
s=x.length();
for(int i=0;i<s;i++)
{
c=0;
for(int j=0;j<s;j++)
{
if(x[j]==x[i])
{
c++;
}
}
if(c>1)
{
w=x[i];
break;
}
}
if(c==0||w==0)
{
cout<<"."<<"\n";
}
else
{
cout<<(char)w<<"\n";
}
}
return 0;
}
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