65. Ripple Carry Adder

How do you plan to solve it?

// 1-bit Full Adder (to be used by the 4-bit RCA)
module full_adder_1bit (
    input  a, b, cin,
    output sum, cout
);

    assign sum = a^b^cin;
    assign cout = (a&b)|(b&cin)|(a&cin);

endmodule

// 4-bit Ripple Carry Adder – chain 4 full adders
module rca4_chain (
    input  [3:0] a,
    input  [3:0] b,
    input        cin,
    output [3:0] sum,
    output       cout
);
    
     wire x,y,z;
    
      full_adder_1bit fa1(a[0],b[0],cin,sum[0],x);
      full_adder_1bit fa2(a[1],b[1],x,sum[1],y);
      full_adder_1bit fa3(a[2],b[2],y,sum[2],z);
      full_adder_1bit fa4(a[3],b[3],z,sum[3],cout);
    


endmodule