include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
int main(){
string A;
bool s=0;
while(getline(cin,A)){
for(int i=0;i<A.size();i++){
if(A.find(A[i])==A.rfind(A[i])){
cout<<A[i]<<endl;
s=1;
}
}
}
if(s==0)
cout<<”no”<<endl;
return 0;
}