36. 4-Input NAND Gate Primitive

How do you plan to solve it?

module nand4_prim (
    input  a,
    input  b,
    input  c,
    input  d,
    output y
);
wire e, f;
    assign e = ~(a & b);
    assign f = ~(c & d);
    assign y = e | f;
endmodule