### Database Schema:
CREATE TABLE SeasonStatus (
	ELITEID	INTEGER	NULL,
	SEASON	TEXT	NULL,
	TEAM	TEXT	NULL,
	LEAGUE	TEXT	NULL,
	GAMETYPE	TEXT	NULL,
	GP	INTEGER	NULL,
	G	INTEGER	NULL,
	A	INTEGER	NULL,
	P	INTEGER	NULL,
	PIM	INTEGER	NULL,
	PLUSMINUS	INTEGER	NULL,
	foreign key (ELITEID) references PlayerInfo (ELITEID)
);

CREATE TABLE weight_info (
	weight_id	INTEGER	NULL	PRIMARY KEY,
	weight_in_kg	INTEGER	NULL,
	weight_in_lbs	INTEGER	NULL
);

CREATE TABLE height_info (
	height_id	INTEGER	NULL	PRIMARY KEY,
	height_in_cm	INTEGER	NULL,
	height_in_inch	TEXT	NULL
);

CREATE TABLE PlayerInfo (
	ELITEID	INTEGER	NULL	PRIMARY KEY,
	PlayerName	TEXT	NULL,
	birthdate	TEXT	NULL,
	birthyear	DATE	NULL,
	birthmonth	INTEGER	NULL,
	birthday	INTEGER	NULL,
	birthplace	TEXT	NULL,
	nation	TEXT	NULL,
	height	INTEGER	NULL,
	weight	INTEGER	NULL,
	position_info	TEXT	NULL,
	shoots	TEXT	NULL,
	draftyear	INTEGER	NULL,
	draftround	INTEGER	NULL,
	overall	INTEGER	NULL,
	overallby	TEXT	NULL,
	CSS_rank	INTEGER	NULL,
	sum_7yr_GP	INTEGER	NULL,
	sum_7yr_TOI	INTEGER	NULL,
	GP_greater_than_0	TEXT	NULL,
	foreign key (height) references height_info (height_id),
	foreign key (weight) references weight_info (weight_id)
);

### User's Query:
What is the weight in kilograms of the player with the highest number of goal differential of all time?

### Extra Knowledge:
weight in kilograms refers to weight_in_kg; highest number of goal differential of all time refers to MAX(PLUSMINUS);
SELECT T3.weight_in_kg FROM SeasonStatus AS T1 INNER JOIN PlayerInfo AS T2 ON T1.ELITEID = T2.ELITEID INNER JOIN weight_info AS T3 ON T2.weight = T3.weight_id ORDER BY T1.PLUSMINUS DESC LIMIT 1