Find the smallest real number \(a\) such that for all real numbers \(x, y, z\) the inequality holds:

\[x^{2}+y^{2}+z^{2}+a \geq x + 2y + 3z\]

Atrast mazāko reālo skaitli \(a\), ar kuru visiem reāliem skaitliem \(x, y, z\) ir spēkā nevienādība:

\[x^{2}+y^{2}+z^{2}+a \geq x + 2y + 3z\]