#include <iostream>
using namespace std;
int main() {
// your code goes here
int t;
cin>>t;
while(t--)
{
string s;
char c='#';
cin>>s;
for(int i=0;i<s.length();i++)
{
for(int j=i+1;j<s.length();j++)
{
if(s[i]==s[j])
{
c=s[i];
break;
}
}
}
if(c=='#')
{
cout<<'.'<<"\n";
}
else
{
cout<<c<<"\n";
}
}
return 0;
}
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