(3) Let the length, width, and height of the rectangular prism be $a$, $b$, and $c$, respectively, and $a+b-c=1$. Given that the length of the diagonal of the rectangular prism is 1, and $a \neq b$, then the range of values for $c$ is $\qquad$
(3) $\left(0, \frac{1}{3}\right)$