B1. The floor function of any real number $a$ is the integer number denoted by $\lfloor a\rfloor$ such that $\lfloor a\rfloor \leq a$ and $\lfloor a\rfloor>a-1$. For example, $\lfloor 5\rfloor=5,\lfloor\pi\rfloor=3$ and $\lfloor-1.5\rfloor=-2$. Find the difference between the largest integer solution of the equation $\lfloor x / 3\rfloor=102$ and the smallest integer solution of the equation $\lfloor x / 3\rfloor=-102$.
Solution: For $\lfloor x / 3\rfloor=102$, we need $103>x / 3 \geq 102$, so $309>x \geq 306$. Thus, $x$ can be 306,307 , or 308. The largest is 308 .

For $\lfloor x / 3\rfloor=-102$, we need $-101>x / 3 \geq-102$, so $-303>x \geq-306$. Thus, $x$ can be $-306,-305$, or -304 . The smallest is -306 .
Answer: $308-(-306)=614$.