module fa( a, b, cin, cout, sum);
input    a, b, cin;
output  cout, sum;

wire  m, n, p;


ha    g1 (.cout(n), .sum(m), .a(a), .b(b) );
ha    g2 (.cout(p), .sum(sum), .a(cin), .b(m) );

assign cout = p | n;

endmodule




`timescale 1ns / 1ns
module fa_tb;

reg       a,  b, cin;
wire     cout, sum;


fa   u1 ( a, b, cin, cout, sum );




initial begin
         {a, b, cin} = 3'b000;
  #10 {a, b, cin} = 3'b001;
  #10 {a, b, cin} = 3'b01_0;
  #10 {a, b, cin} = 3'b011;
  #10 {a, b, cin} = 4;
  #10 {a, b, cin} = 5;
  #10 {a, b, cin} = 6;
  #10 {a, b, cin} = 7;
  #10 $stop;
end

initial $monitor($time, "ns, a=%b, b=%b, cin = %b, cout=%b, sum=%b", a, b, cin, cout, sum);

endmodule