Maratona de Programação da SBC Brasil
It will be give to you N points on a circle. You must write a program to determine how many distinct equilateral triangles can be constructed using the given points as vertices.
The figure below illustrates an example: (a) shows a set of points, determined by the lengths of the circular arcs that have adjacent points as extremes; and (b) shows the two triangles which can be built with these points.
The input contains several test cases and ends with EOF. The first line of a test case contains an integer N ( 3 ≤ N ≤ 105), the number of points given. The second line contains N integers Xi (1 ≤ Xi ≤ 103) for 1 ≤ i ≤ N, representing the lengths of the circular arcs between two consecutive points in the circle: for 1 ≤ i ≤ (N − 1), Xi represents the length of the arc between points i and i + 1; XN represents the length of the arc between points N and 1.
For each test case your program must output a single line, containing a single integer, the number of distinct equilateral triangles that can be constructed using the given points as vertices.
|Sample Input||Sample Output|