CREATE TABLE Users(
uid int PRIMARY KEY,
name text,
phone text
);
CREATE TABLE Messages(
recipient int REFERENCES Users(uid),
sender int REFERENCES Users(uid),
time timestamp NOT NULL,
message text NOT NULL,
PRIMARY KEY (recipient, sender, time)
);

SELECT COUNT(distinct U2.uid)
FROM Users U2,Messages M
WHERE M.sender=U2.uid AND U2.name<>'Freddy'  AND M.recipient=(SELECT  U.uid FROM Users U,Messages M
WHERE M.recipient=U.uid AND M.sender=(SELECT uid FROM Users where name='Freddy'))