Travelling Chef Problem

When Chef is travelling - that's the problem. No one knows when he will change his velocity. But mathematicians are certain that Chef's velocity depends on the current time, and can be described as a cubic polynomial. A cubic polynomial can be defined as: v(t) = A×t3 + B×t2 + C×t + D, where A, B, C, D are rational numbers (A is non zero), and t is the current time. As for us, all we know is: Che