The symbols $\lfloor x\rfloor$ and $\lceil x\rceil$ mean the greatest integer less than or equal to x and the least integer greater than or equal to x, respectively. So, $\lfloor0.999\rfloor$ is the greatest integer that is less than or equal to 0.999, which is 0. Similarly, $\lceil2.001\rceil$ is the least integer that is greater than or equal to 2.001, which is 3. Therefore, $\lfloor0.999\rfloor+\lceil2.001\rceil=0+3=3$. 
Evaluate $\lfloor0.999\rfloor+\lceil2.001\rceil$.