Problem A
The Brick Stops Here
You have been hired by several clients of a factory that manufactures brass bricks. Brass is an alloy of copper and zinc; each brick weighs $1000$ grams, and the copper content of a brick can range from $1$ to $999$ grams. (Note that brass with less than 55% or more than 62% of copper is practically useless; however, this is irrelevant for this question.) The factory manufactures, through various processes, different types of brick, each of which has a different copper concentration and price. It distributes a catalog of these types to its customers.
Your clients desire to buy a certain number ($M$) of bricks, which for, uh, religious reasons must be of different types. They will be melted together, and the resultant mixture must have a concentration of at least $C_\text {min}$ and at most $C_\text {max}$ grams of copper per kilogram. Their goal is to pick the $M$ types of brick so that the mixture has the correct concentration and the price of the collection is minimized. You must figure out how to do this. $M$, $C_\text {min}$, and $C_\text {max}$ will vary depending on the client.
Input
The first part of input consists of a line containing a number $N$ ($1 \le N \le 250$), the number of brick types, and then $N$ lines containing the copper concentration (between $1$ and $999$) and price (in cents) of each brick type. No brick costs more than $100$ dollars.
The second part consists of a line containing a number $C$ ($1 \le C \le 500$), the number of clients you are serving, followed by $C$ lines containing $M$ ($1 \le M \le 50$), $C_\text {min}$ and $C_\text {max}$ ($1 \le C_\text {min} \le C_\text {max} \le 999$) for each client.
All input numbers are positive integers.
Output
Output consists of a line for each client containing the minimum possible price (in cents) for which they can purchase bricks to meet their demands. If there is no way to match their specifications, output “impossible”.
Sample Input 1 | Sample Output 1 |
---|---|
11 550 300 550 200 700 340 300 140 600 780 930 785 730 280 678 420 999 900 485 390 888 800 3 2 500 620 9 550 590 9 610 620 |
420 impossible 3635 |