Question: Consider the sequence of digits from 1 through N in increasing order: 1 2 3 ... N.

Now insert either a '+' for addition or a '-' for subtraction or a ' ' [blank] to run the digits together between each pair of digits (not in front of the first digit). Calculate the result that of the expression and see if you get zero. Consider: 1-2 3-4 5+6 7. This translates to 1 – 23 – 45 + 67 = 0. Write a program that will find all sequences of length N that produce a zero sum.

Input specification: You will be given an integer N (3<=N<=9) which is the last number of the sequence.

Output specification: You are required to give all the possible solutions for this sequence or "Impossible" if none is found. Note: Use the order: blank, + and -.