Problem:
Score : 200 points

Problem Statement

We have sticks numbered 1, \cdots, N. The length of Stick i (1 \leq i \leq N) is L_i.

In how many ways can we choose three of the sticks with different lengths that can form a triangle?

That is, find the number of triples of integers (i, j, k) (1 \leq i < j < k \leq N) that satisfy both of the following conditions:

L_i, L_j, and L_k are all different.

There exists a triangle whose sides have lengths L_i, L_j, and L_k.

Constraints

1 \leq N \leq 100

1 \leq L_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
L_1 L_2 \cdots L_N

Output

Print the number of ways to choose three of the sticks with different lengths that can form a triangle.

Sample Input 1

5
4 4 9 7 5

Sample Output 1

5

The following five triples (i, j, k) satisfy the conditions: (1, 3, 4), (1, 4, 5), (2, 3, 4), (2, 4, 5), and (3, 4, 5).

Sample Input 2

6
4 5 4 3 3 5

Sample Output 2

8

We have two sticks for each of the lengths 3, 4, and 5. To satisfy the first condition, we have to choose one from each length.

There is a triangle whose sides have lengths 3, 4, and 5, so we have 2 ^ 3 = 8 triples (i, j, k) that satisfy the conditions.

Sample Input 3

10
9 4 6 1 9 6 10 6 6 8

Sample Output 3

39

Sample Input 4

2
1 1

Sample Output 4

0

No triple (i, j, k) satisfies 1 \leq i < j < k \leq N, so we should print 0.

Solution in C# (.NET Core 3.1.201) (judge verdict: Accepted)


using System;
using System.Collections.Generic;

class IDONTKNOWCSHARP
{
    public static void Main()
    {
        int num = int.Parse(Console.ReadLine());
        long[] values = Convert(Console.ReadLine().Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries));
        int count = 0;
        List<(long, long, long)> list = new List<(long, long, long)>();

        Array.Sort(values);
        for (int i1 = 0; i1 < num-2; i1++)
        {
            for (int i2 = i1 + 1; i2 < num-1; i2++)
            {
                for (int i3 = i2 + 1; i3 < num; i3++)
                {
                    //    Console.WriteLine($"{values[i1] },{values[i2]},{values[i3]}");
                    if (values[i1] + values[i2] > values[i3] && values[i1] != values[i2] && values[i2] != values[i3])
                    {

                        //  if (!list.Any(x => x == (values[i1], values[i2], (values[i3]))))
                        //     {
                        list.Add((values[i1], values[i2], values[i3]));
                        count++;
                        //    }
                    }
                }
            }
        }


        Console.WriteLine(count);
      //  Console.ReadKey();
    }

    static long[] Convert(string[] str)
    {
        long[] temp = new long[str.Length];
        for (int i = 0; i < temp.Length; i++)
        {
            temp[i] = long.Parse(str[i]);
        }
        return temp;
    }
}