SELECT COUNT(COMU.COMUNIDADI) FROM
(
        SELECT COMUNIDADI FROM
        COMUNIDADXTRAMO
        WHERE COMUNIDADI IN
        (
                SELECT COMUNIDADF
                FROM COMUNIDADXTRAMO
                WHERE ID_TRAMO IN
                (
                        SELECT ID_TRAMO
                        FROM TRAMO
                        WHERE ID_TIPO=
                                (
                                SELECT ID_TIPOT
                                FROM TIPO_TRAMO
                                WHERE NOMBRE='FINAL'
                                )
                )
                ORDER BY COMUNIDADF
        )
        AND ID_TRAMO IN
        (
                SELECT ID_TRAMO
                FROM TRAMO
                WHERE ID_TIPO=
                (
                        SELECT ID_TIPOT
                        FROM TIPO_TRAMO
                        WHERE NOMBRE='INICIAL'
                )
        )
        ORDER BY COMUNIDADI
 ) AS COMU