Figure shows two sequence x 1 [n] and x 2 [n]. The value of x 2 [n]

Question:

Figure shows two sequence x₁[n] and x₂[n]. The value of x₂[n] at time n = 3 is not known, but is shown as a variable ?. Figure shows y[n], the four-point circular convolution of x₁[n] and x₂[n]. Based on the graph of y[n], can you specify ? uniquely? If so, what is a? If not, give two possible values of a would yield the sequence y[n] as shown.