On a frictionless horizontal plane, a bob of mass $\mathrm{m}=0.1 \mathrm{~kg}$ is attached to a spring with natural length $\mathrm{l} 0=0.1$ m . The spring constant is $\mathrm{k}_1=0.009 \mathrm{Nm}^{-1}$ when the length of the spring $\mathrm{I}>\mathrm{l} \mathrm{o}$ and is $\mathrm{k}_2=0.016 \mathrm{Nm}^{-1}$ when $\mathrm{I}<$ 10. Initially the bob is released from $\mathrm{I}=0.15 \mathrm{~m}$. Assume that Hooke's law remains valid throughout the motion. If the time period of the full oscillation is $T=(n \pi) s$, then the integer closest to $n$ is