module average(a1,b,clk,C);

input [9:0] a1;
input clk,b;
output [9:0]C;
reg [9:0] in1,in2,in3,in4,avg;
reg [11:2] Sum;

always @ (a1,posedge clk);

begin

 0:in1=a1;
 1:in2=in1;
 2:in3=in2;
 3:in4=in3;
 in1+in2+in3+in4=Sum;
 Sum/4=C
 
end
endmodule