сортировка списков

program lst;
type
list=^s;
s=record
inf:integer;
next,pred:list;
end;
var
n,i,k,k1,k3,t,k4:integer;
p,q,first,last,k2:list;
procedure sort(i:integer);
var
l,s,c,f:list;
o,j:integer;
begin
first^.pred:=last;
q:=p;
p:=first;
for j:=1 to n do begin
q:=last;
for i:=1 to n do begin
if (q^.pred^.inf>q^.inf) then begin
l^.inf:=q^.inf;
q^.inf:= q^.pred^.inf;
q^.pred^.inf:=l^.inf; 
end;
q:=q^.pred;
end;
p:=p^.next;
end;
q:=first;
for i:=1 to n do begin
write(q^.inf:3);
q:=q^.next;
end;
end;
begin
randomize;
new(first);
p^.inf:=random(10);
q:=first;
writeln;
writeln('vvedite razmer massiva:: ');
read(n);
for i:=1 to n do begin
new(p);
p^.inf:=random(50);
q^.next:=p;
p^.pred:=q;
q:=p;
end;
p:=first;
writeln('vivod v napravlenii ot 0 do n:');
for i:=1 to n do begin
write(p^.inf:3);
p:=p^.next
end;
last:=p;
writeln;
writeln('vivod v napravlenii n do 0:');
p:=p^.pred;
for i:=1 to n do begin
write(p^.inf:3);
p:=p^.pred;
end;
writeln;
writeln('otsortirovannyi massiv:') ;
sort(k);
readln(t);
end.