Checking whether the constant added after all layers is even or odd .
if ( beven ) { if ( ( b & 1 ) > 0 ) beven = false ; } else if ( ! ( ( a & 1 ) > 0 ) ) { if ( ! ( ( b & 1 ) > 0 ) ) beven = true ; } else { if ( ( b & 1 ) > 0 ) beven = true ; } }