lets STUDY

program penjumlahan_angkagenap;
uses wincrt;
var i,j,n,sum :integer;
begin
readln (n);
if n=1 then write ('0') else
if n>1 then
begin
sum:=0;
for i:=n downto 2 do
begin
j:=(2*i-2);
write (j,'+');
sum:=sum+j;
end;
writeln (0,'=',sum);
end;
end.