подскажите сборник задач с решениями по процедурам и функциям на Turbo Pascal

процедур существует 4 типа, вот они все, что не ясно, пиши
{program proc1_4; } {tip_1 0 vo vxoge, o na vixode}
{uses crt;
procedure f1;
var
a,b,c: integer;
begin
write('vvesti 2 chisla -->'); readln(a,b);
c:=a + b;
writeln('summa = ',c);
end;
BEGIN
clrscr;
writeln('vichislenie summ chisl a and b');
writeln('--------------------------------');
writeln;
f1;
writeln('------------------');
writeln('konec zadachi');
readkey;
END. }
{ program proc1_4; } {tip_2 2 vo vxoge, o na vixode}
{ uses crt;
var
a,b: integer;
procedure f2(x,y:integer);
var
c: integer;
begin
c:=x + y;
writeln('summa = ',c);
end;
BEGIN
clrscr;
writeln('vichislenie summ chisl a and b');
writeln('--------------------------------');
writeln;
write('vvesti 2 chisla -->'); readln(a,b);
f2(a,b);
writeln('------------------');
writeln('konec zadachi');
readkey;
END. }
{ program proc1_4;} {tip_3 0 vo vxoge, 1 na vixode}
{ uses crt;
var
c: integer;
procedure f3(var s:integer);
var
a,b: integer;
begin
writeln('vichislenie summ chisl a and b');
writeln('--------------------------------');
writeln;
write('vvesti 2 chisla -->'); readln(a,b);
s:=a + b;
writeln('summa = ',s);
end;
BEGIN
clrscr;
f3(c);
writeln('------------------');
writeln('konec zadachi');
readkey;
END. }
program proc1_4; {tip_4 2 vo vxoge, 1 na vixode}
uses crt;
var
a,b,c: integer;
procedure f4(x,y:integer;var z:integer);
begin
z:=x + y;
end;
BEGIN
clrscr;
writeln('vichislenie summ chisl a and b');
writeln('--------------------------------');
writeln;
write('vvesti 2 chisla -->'); readln(a,b);
c:=a + b;
f4(a,b,c);
writeln('summa = ',c);
writeln('------------------');
writeln('konec zadachi');
readkey;
END.