Let's consider so called "sly number" which is given as an array A of N integers from set {0,1,2}. For example A[0]=1, A[1]=1, A[2]=0 and A[3]=2. A sly number is called ONE, if A[0]=1 and A[I]=0 for I=1,2,?,N-1.
Consider following operation with two sly numbers A and B called 'Star Multiplication':
k N-1
C[k] = ∑ A[i] * B[k-i] + ∑ A[i] * B[N+k-i].
i=0 i=k+1
here C ? the result of the operation, even also presented in an array - not necessarily sly number. This operation we will denote by <*> symbol.
Moreover, there is also module operation over the results of 'Star Multiplication':
(C mod Q) [i] = C[i] mod Q,
where Q is a positive integer.
We are given a sly number A and a module Q. We need to find such 'inverse sly number' B:
(A * B) mod Q = ONE.