Problem 5 (20): Prove that the following languages are not CF. \text { (a) } L=\left\{d^{n} b^{n} c^{n} \mid n \geq 0\right\} \text { (b) } L=\left\{w \mid w \in\{a,

b, c\}^{*} \text { and } w \text { has an equal number of } a^{\prime} s, b^{\prime} s \text { , and } c^{\prime} s\right\}