module top;

   reg    clk;
   reg 	  rst;
   port   clkrst vars clk:clk, rst:rst;
         
   always #5 clk = ~clk;
    
   initial
      begin
	 // initial values
	 clk = 0;
	 
	 // reset system
	 rst = 1'b0; // negate reset
	 #2;
	 rst = 1'b1; // assert reset
	 repeat(4) @(posedge clk);
	 rst = 1'b0; // negate reset
      end
endmodule