#include <bits/stdc++.h>
using namespace std;
int main() {
// your code goes here
int t;
cin>>t;
while(t--)
{
unordered_map<char,int>m;
string s;
int c=0;
cin>>s;
for(int i=0;i<s.length();i++)
{
m[s[i]]++;
}
for(auto i:m)
{
if(i.second>=2)
{
cout<<i.first<<"\n";
c++;
break;
}
}
if(c<1)
{
cout<<"."<<'\n';
}
}
return 0;
}
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