For the given alphabet $\backslash$Sigma $=\{$a$,$b$,$c$,$d$,$e$\},$ define a language where the letters $\text{'}$a$\text{'}$ and $\text{'}$c$\text{'}$ must both appear in any valid string, and the letters $\text{'}$d$\text{'}$ and $\text{'}$e$\text{'}$ must both appear in any valid string. However, $\text{'}$a$\text{'}$ and $\text{'}$c$\text{'}$ cannot appear in the same string as $\text{'}$d$\text{'}$ and $\text{'}$e$\text{'}$