### Database Schema:
CREATE TABLE PaperAuthor (
	PaperId	INTEGER	NULL,
	AuthorId	INTEGER	NULL,
	Name	TEXT	NULL,
	Affiliation	TEXT	NULL,
	foreign key (AuthorId) references Author (Id),
	foreign key (PaperId) references Paper (Id)
);

CREATE TABLE Author (
	Id	INTEGER	NULL	PRIMARY KEY,
	Name	TEXT	NULL,
	Affiliation	TEXT	NULL
);

CREATE TABLE Paper (
	Id	INTEGER	NULL	PRIMARY KEY,
	Title	TEXT	NULL,
	Year	INTEGER	NULL,
	ConferenceId	INTEGER	NULL,
	JournalId	INTEGER	NULL,
	Keyword	TEXT	NULL,
	foreign key (JournalId) references Journal (Id),
	foreign key (ConferenceId) references Conference (Id)
);

CREATE TABLE Journal (
	Id	INTEGER	NULL	PRIMARY KEY,
	ShortName	TEXT	NULL,
	FullName	TEXT	NULL,
	HomePage	TEXT	NULL
);

CREATE TABLE Conference (
	Id	INTEGER	NULL	PRIMARY KEY,
	ShortName	TEXT	NULL,
	FullName	TEXT	NULL,
	HomePage	TEXT	NULL
);

### User's Query:
From year 1991 to 2000, calculate the difference betweeen the total number of papers published under the conference "International Conference on Supercomputing " and "Informatik & Schule"?

### Extra Knowledge:
From year 1991 to 2000 refers to Year BETWEEN 1991 AND 2000; papers refers to Paper.Id; 'International Conference on Supercomputing' AND 'Informatik & Schule' are the FullName of conference; calculate the difference between the total number of papers of these two conferences refers to SUBTRACT(SUM(Paper.Id where FullName = 'International Conference on Supercomputing'), SUM(Paper.Id where FullName = 'Informatik & Schule'))
SELECT SUM(CASE WHEN T2.FullName = 'Informatik & Schule' THEN 1 ELSE 0 END) - SUM(CASE WHEN T2.FullName = 'International Conference on Supercomputing' THEN 1 ELSE 0 END) AS DIFF FROM Paper AS T1 INNER JOIN Conference AS T2 ON T1.ConferenceId = T2.Id WHERE T1.Year > 1990 AND T1.Year < 2001