Consider a finite state machine (FSM) with one input \(X\) and one output \(f\), represented by the given state transition table. The minimum number of states required to realize this FSM is __________ (Answer in integer).
Examining the transition table shows that some states behave identically in all situations. In particular, states A, B, and H always respond in the same way, regardless of the input. Similarly, states F and C cannot be distinguished from each other, and states D, G, and E also exhibit identical behavior.
Since no input sequence can separate the states within each of these sets, they can be treated as single states without changing the behavior of the machine.
After combining these indistinguishable states, the machine consists of exactly five distinct behaviors.
Hence, the minimum number of states required is \(\boxed{5}\).