PIGBANK  PiggyBank
Before ACM can do anything, a budget must be prepared and the necessary financial support obtained. The main income for this action comes from Irreversibly Bound Money (IBM). The idea behind is simple. Whenever some ACM member has any small money, he takes all the coins and throws them into a piggybank. You know that this process is irreversible, the coins cannot be removed without breaking the pig. After a sufficiently long time, there should be enough cash in the piggybank to pay everything that needs to be paid.
But there is a big problem with piggybanks. It is not possible to determine how much money is inside. So we might break the pig into pieces only to find out that there is not enough money. Clearly, we want to avoid this unpleasant situation. The only possibility is to weigh the piggybank and try to guess how many coins are inside. Assume that we are able to determine the weight of the pig exactly and that we know the weights of all coins of a given currency. Then there is some minimum amount of money in the piggybank that we can guarantee. Your task is to find out this worst case and determine the minimum amount of cash inside the piggybank. We need your help. No more prematurely broken pigs!
Input
The input consists of T test cases. The number of them (T) is given on the first line of the input file. Each test case begins with a line containing two integers E and F. They indicate the weight of an empty pig and of the pig filled with coins. Both weights are given in grams. No pig will weigh more than 10 kg, that means 1 <= E <= F <= 10000. On the second line of each test case, there is an integer number N (1 <= N <= 500) that gives the number of various coins used in the given currency. Following this are exactly N lines, each specifying one coin type. These lines contain two integers each, Pand W (1 <= P <= 50000, 1 <= W <=10000). P is the value of the coin in monetary units, W is it's weight in grams.
Output
Print exactly one line of output for each test case. The line must contain
the sentence
"The minimum amount of money in the piggybank is X.
"
where X is
the minimum amount of money that can be achieved using coins with
the given total weight. If the weight cannot be reached exactly,
print a line "This is impossible.
".
Example
Sample Input: 3 10 110 2 1 1 30 50 10 110 2 1 1 50 30 1 6 2 10 3 20 4 Sample output: The minimum amount of money in the piggybank is 60. The minimum amount of money in the piggybank is 100. This is impossible.
hide comments
shahi9935:
20180122 10:45:15
@hsakiv220290 Third case is impossible because. There are only two weights 4 and 3 and any combination of them can't lead to total weight of 5(61) 

steven_lin1:
20180116 20:59:29
I am getting an NZEC on this one even though all of my samples are correct AND I ran a few more samples that required a fair amount of computation. 

steven_lin1:
20180116 20:55:41
Getting a NZEC error on this one and all three of my samples are correct. Plus I ran quite a few more examples too. Any thoughts? 

hsakiv220290:
20180114 10:33:21
the outout of 3rd test is 20. what is the problem in that? 

chetan4060:
20171215 16:18:12
unbounded knapsack with some changes will do:) 

kmkhan_014:
20171129 11:14:34
dont forget the period.!


sanchit kwatra:
20171115 20:15:20
AC in one go!


nadstratosfer:
20171110 11:29:24
Thanks steady_bunny for the crucial test case. Managed AC with raw Python, always hard in this type of problems. A little lesson in optimizing interpreted languages: refactored the code to have 3 statements less in the main loop  same complexity  time improved by whopping 0.85s. More workout and fun than I had expected to find here. 

dwij28:
20170925 22:03:29
TLE in CPython and Accepted in PyPy. That's just bad. 1D easy DP duh :) 

rohit9934:
20170903 10:50:46
It is a slight modification of unbounded knapsack, Just store min of price, int will go fine. 
Added by:  adrian 
Date:  20040606 
Time limit:  5s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All 
Resource:  ACM Central European Programming Contest, Prague 1999 