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.ComponentModel.Design;
using System.Collections.Generic;
using System;
using System.Linq;
using static System.Console;

class P
{
    static void Main()
    {
        var d = new Dictionary<int, int>();
        var n = int.Parse(ReadLine());
        var l = ReadLine().Split().Select(int.Parse).ToList();
        foreach (var e in l)
        {
            if (d.ContainsKey(e)) d[e]++;
            else d[e] = 1;
        }
        var keys = d.Keys.OrderBy(x => x).ToList();
        var ans = 0;
        if (l.Count >= 3)
        {
            for (int i = 0; i < keys.Count - 2; i++)
            {
                for (int j = i + 1; j < keys.Count - 1; j++)
                {
                    for (int k = j + 1; k < keys.Count; k++)
                    {
                        int first = keys[i], second = keys[j], third = keys[k];
                        var max = new int[] {first, second, third}.Max();
                        var sum = first + second + third;
                        if (first == second || second == third || third == first) break;
                        if (max >= sum - max) break;
                        ans += d[first] * d[second] * d[third];
                    }
                }
            }
        }
        WriteLine(ans);
    }
}