GATE EC 2017 Set 1 Q18 — Control Systems

The open loop transfer function $$G(s)=\frac{(s+1)}{s^{p}(s+2)(s+3)}$$ where $p$ is an integer, is connected in unity feedback configuration as shown in figure.

Given that the steady state error is zero for unit step input and is $6$ for unit ramp input, the parameter $p$ is__________.