simulink: solving differential equations

Hello guys I have transfer function which is below. And I need to create block diagram in simulink without using block "transfer function". I find out that I can use corresponding differential equation which should look like this:

a2*y'' + a1*y' + 1 = K*u

                  K
 transfer f= ----------------
              a2*s^2 + a1*s + 1

Here is my solution but I don't think it's correct, because I think I'm missing the part (+1) from differential equation.

So can somebody help me how should I fix it?