lets STUDY

program bintang;
uses wincrt;
var i,j,n :integer;
begin
readln (n);
for i:=2*n-1 downto 1 do
begin
for j:=n downto 1 do
begin
if ((j>i) or (j>(2*n-1)-i+1)) then
write (' ') else
write ('*');
end;
writeln ;
end;
end.