A critical system component has three backup channels, $C_1, C_2,$ and $C_3$. The system functions if $C_1$ works, OR if both $C_2$ and $C_3$ work. The probabilities of functioning are $P(C_1) = 0.8$, $P(C_2) = 0.7$, and $P(C_3) = 0.6$. Assuming the channels fail independently, what is the probability that the system fails to function?