uses crt;
var m,n,dem,i:integer;
begin
clrscr;
write('m='); readln(m);
write('n='); readln(n);
if m<n then
begin
dem:=0;
for i:=m to n do
if i mod 3=0 then inc(dem);
writeln('co ',dem,' so chia het cho 3 trong pham vi tu ',m,' toi ',n);
end
else writeln('vui long nhap lai');
readln;
end.