Alternate Universe

Codechef has been founded in an alternate universe, and here the rating system works weirdly. There are $N$ rated contests, and you will be taking part in them. In the $i$-th contest, if your rating $R$ is at most $A_i$, you can choose to get an increase in your rating in the range $[0, B_i]$, i.e. you may choose to increase your rating by any integer $X$ satisfying $0 \le X \le B_i$. Further,