Design pulse-mode circuits using sr ffs that responds to

Question

Design pulse-mode circuits using SR FFs that responds to two inputs, x₁ and x₂. An output is generated coincident with the last of a sequence of four input impulses if and only if the sequence contained:

(a) at least two x₁ pulses,

(b) at least three x₁ pulses,

(c) at most two x₁ pulses, and

(d) at most three x₁ pulses.