var n,i,s:integer;
a:array[1..1000] of integer;
begin
a[1]:=1;
write('n=');
read(n);
for i:=2 to n do 
a[i]:=a[i-1]+2;
for i:=1 to n do
s:=s+a[i];
write('Ответ:',s);
end.