Query a value in the firebase realtime database

I want to check if a certain value is in the database. What I'm trying to do is get the value reference to consult and do the tour and if it finds an equal value, I print a toast, and count how many times it found the value. Here he is not doing it and I think it's the way I get the reference.

The references to the database are in a separate class, for this case I would like to consult in this class the reference to the document field "doc".

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_pollamundialista);

    enviar = (ImageButton) findViewById(R.id.enviar1);
    //Datos personales
    nom = (EditText) findViewById(R.id.nom);
    doc = (EditText) findViewById(R.id.doc);
    email = (EditText) findViewById(R.id.email);
    phone = (EditText) findViewById(R.id.phone);
    //Predicciones
    a1a2_a1 = (EditText) findViewById(R.id.a1a2_a1);
    a1a2_a2 = (EditText) findViewById(R.id.a1a2_a2);

    final DatabaseReference uniagust = database.getReference(FirebaseReferences.REFERENCE_1);
    final DatabaseReference polla = database.getReference(FirebaseReferences.REFERENCE_2);

    //Consulta
    //bbdd = FirebaseDatabase.getInstance().getReference(FirebaseReferences.REFERENCE_2);


    enviar.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            //Consultando una referencia
            Query q=uniagust.orderByChild("doc").equalTo("963258");
            q.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    int cont=0;
                    for(DataSnapshot datasnapshot: dataSnapshot.getChildren()){
                        cont++;
                        Toast.makeText(PollaMundialista.this, "Encontrado "+cont, Toast.LENGTH_LONG).show();
                    }
                    if(cont<0){
                        Toast.makeText(PollaMundialista.this, "El valor no se encuentra registrado"+cont, Toast.LENGTH_LONG).show();                            
                    }

                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
        }
    });


}

The firebase database is displayed like this:

References class:

public class FirebaseReferences {
final public static String REFERENCE_1 = "uniagust";
final public static String REFERENCE_2 = "polla";
}