Each of M, N and P is a 4 digit non-leading zero positive integer such that:
- M+N=P
- The digits of each of M,N and P are distinct.
- Each of M, N and P are permutations of one another.
Determine all possible triplets (M,N,P).
Permuting a number does not change its value mod 9.
Therefor, M = N = P mod 9
Also, M + N = P mod 9.
Therefore, 2P = P mod 9
Therefore M = N = P = 0 mod 9