uses crt;
var a,b,i: integer;
begin
clrscr;
    write('a='); readln(a);
    write('b='); readln(b);
    write('Cac so chia het cho 3 la: ');
    if b>a then for i:=b downto a do if i mod 3 = 0 then write(i,' ');
    if b<a then for i:=a downto b do if i mod 3 = 0 then write(i,' ');
    readln
end.

uses crt;
var i,s,j,tam,a,b:integer;
p:array[1..100] of integer;
begin
clrscr;
write('nhap so a:');readln(a);
write('nhap so b:');readln(b);
while a>b do
begin
 write('nhap lai b:');
 readln(b);
end;
for i:=a to b do
begin
 write('A[',i,']=');
 readln(p[i]);
 if p[i] =10 then s:=s+1;
 end;
for i:=a to b do
for j:=a+1 to b do
 if p[i] < p[j] then
 begin
  tam:=p[i];
  p[i]:=p[j];
  p[j]:=tam;
 end;
write('cac so chia het cho 3 theo thu tu giam dan la:');
for i:=a to b do
 if (p[i] mod 3=0)and(p[i] <>0)  then write(p[i]:3);
readln;
end.

(mong dc 5*+hay nhất)