CODEM2  Problem2
Two boxes contain the same total numbers of balls having some blacks and some whites in each.From each box "n" number of balls are drawn with replacement.Find the number of white balls in box A if composition of box B is given and such that probability that all white balls are drawn from box A is equal to the probability that the drawing from box B is either all whites or all blacks for the given number of drawings.
Input
T:no of testcases
Next T lines contain 3 integers n,x,y.
Output
For each testcase print in new line "impossible" if it is not possible to find no of white balls in box A else print no of white balls.
Example
Input: 1
2 3 4 Output: 5
Constraints:
1<=n<=1000
1<=x,y<=1000
x=no of white balls in box B , y=no of black balls in box B
hide comments
mahilewets:
20170908 21:41:45
P(A, W) is probability that all n balls drawn from box A are white


zubenkoivan:
20170809 18:38:46
please add more test cases 

racsosabe16:
20170622 20:00:04
I couldn't understand correctly the problem >:V 
Added by:  Bhavik 
Date:  20140204 
Time limit:  0.5s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 
Resource:  own problem(for CODE MARATHON) 