var n: longint;

function F(n: longint): longint;

begin

if n < 3

then F := 2

else if (((n mod 2) = 0) and (n > 2))

then F := F(n - 2) + F(n-1) - n

else if (((n mod 2) <> 0) and (n > 2))

then F := F(n - 1) - F(n - 2) + 2 * n;

end;

begin

writeln(F(32));

end.

f=[0]+[2]*2+[0]*30

for n in range(3, 33):

if n%2==1:

f[n]=f[n-1]-f[n-2]+2*n

else:

f[n]=f[n-1]+f[n-2]-n

print(f[32])