64. Full Adder

How do you plan to solve it?

// Half Adder primitive
module half_adder (
    input  a, b,
    output sum, carry
);
    // Write code here
xor(sum,a,b);
and(carry,a,b);
endmodule

// Full Adder using 2 Half Adders
module full_adder_struct (
    input  a, b, cin,
    output sum, cout
);
    // Write code here
wire sum1,carry1,carry2;
//half_adder ha1(.a(a),.b(b),.sum(sum1),.carry(carry1));
half_adder ha1(a,b,sum1,carry1);
half_adder ha2(sum1,cin,sum,carry2);
//half_adder ha2(.a(sum1),.b(cin),.sum(sum),.carry(carry2));
or(cout,carry1,carry2);
endmodule