K-map to circuit (one group)

Implement the function f described by the Karnaugh map below. The four inputs arrive as a vector x[4:1]; columns give x[1] and x[2], rows give x[3] and x[4]. Cells marked d are don't-cares.

	x1'x2'	x1'x2	x1x2	x1x2'
x3'x4'	d	0	d	d
x3'x4	0	0	d	d
x3x4	1	1	d	d
x3x4'	1	1	0	d

For grading, treat every d as 0 — that is the assignment the minimal solution produces, leaving the four 1s as the only cells where f is 1.