var
i, n: integer;
sum: real;
begin
readln(n);
sum := 0;
for i := 1 to n do
begin
sum := sum + (2 * i - 1);
end;
writeln(sum);
end.
var
i, n: integer;
sum: real;
begin
readln(n);
sum := 0;
for i := 1 to n do
begin
sum := sum + (2 * i - 1);
end;
writeln(sum);
end.