Let \( A \) be a \( 2 \times 2 \) symmetric matrix such that
and the determinant of \( A \) be \( 1 \).
If \( A^{-1} = \alpha A + \beta I, \) where \( I \) is an identity matrix of order \( 2 \times 2 \), then \( \alpha + \beta \) equals _______________ .