Three numbers x, y and z are said to satisfy the triangle inequality if x + y > z, x + z > y, and y + z > x.
The sequence of integers b, b, ..., b[n-1] is said to be triangular if b[i], b[j] and b[k] satisfy the triangle inequality for all distinct values of i, j and k.
You are given an integer sequence as a int a. Return the length of the longest subsequence of a that is triangular. A subsequence of a sequence is obtained by removing zero or more elements from the sequence.
|-||a will contain between 1 and 50 elements, inclusive.|
|-||Each element of a will be between 1 and 10^9, inclusive.|