### Database Schema:
CREATE TABLE unemployed (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE disabled (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE male (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE no_payment_due (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	bool	TEXT	NULL,
	foreign key (bool) references bool (name),
	foreign key (name) references person (name)
);

CREATE TABLE enrolled (
	name	TEXT	NOT NULL	PRIMARY KEY,
	school	TEXT	NOT NULL	PRIMARY KEY,
	month	INTEGER	NOT NULL	DEFAULT 0,
	foreign key (name) references person (name)
);

CREATE TABLE longest_absense_from_school (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	month	INTEGER	NULL	DEFAULT 0,
	foreign key (name) references person (name)
);

CREATE TABLE bool (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY
);

CREATE TABLE enlist (
	name	TEXT	NOT NULL,
	organ	TEXT	NOT NULL,
	foreign key (name) references person (name)
);

CREATE TABLE filed_for_bankrupcy (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE person (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY
);

### User's Query:
What is the longest time for a student from the navy department to be absent from school?

### Extra Knowledge:
navy department refers to organ = 'navy'; longest time to be absent from school refers to MAX(month)
SELECT T1.month FROM longest_absense_from_school AS T1 INNER JOIN enlist AS T2 ON T1.`name` = T2.`name` WHERE T2.organ = 'navy' ORDER BY T1.`month` DESC LIMIT 1