回帖：program year;
var y:integer;
begin
write('please enter the year!');
read(y);
if y mod 4=0 then do
begin
if y mod 100=0 then do
begin
if y mod 400=0 then do write('No!');
else write('Yes!');
end;
else write('No!');
end;
else write('No!');
readln;
end.