module top;
reg [0:3] a, b;
always b = #5 a;
initial begin
a = #1 1;
$monitor("%2d %b %b", $time, a, b);
#1; a = 0;
#1; a = 'he;
#1;
#10; a = 'h5;
#10;
$finish;
end
endmodule