Simple Harmonic Motion

On a frictionless horizontal plane, a bob of mass m=0.1‌kg is attached to a spring with natural length l0=0.1m. The spring constant is k1=0.009Nm−1 when the length of the spring l>l0 and is k2=0.016Nm−1 when l<l0. Initially the bob is released from l=0.15m. Assume that Hooke's law remains valid throughout the motion. If the time period of the full oscillation is T=(nπ)s, then the integer closest to n is