|Educational Codeforces Round 23|
After returning from the army Makes received a gift — an array a consisting of n positive integer numbers. He hadn't been solving problems for a long time, so he became interested to answer a particular question: how many triples of indices (i, j, k) ( i < j < k), such that a i·a j·a k is minimum possible, are there in the array? Help him with it!
The first line of input contains a positive integer number n (3 ≤ n ≤ 105) — the number of elements in array a. The second line contains n positive integer numbers a i (1 ≤ a i ≤ 109) — the elements of a given array.
Print one number — the quantity of triples (i, j, k) such that i, j and k are pairwise distinct and a i·a j·a k is minimum possible.
1 1 1 1
1 3 2 3 4
1 3 3 1 3 2
In the first example Makes always chooses three ones out of four, and the number of ways to choose them is 4.
In the second example a triple of numbers (1, 2, 3) is chosen (numbers, not indices). Since there are two ways to choose an element 3, then the answer is 2.
In the third example a triple of numbers (1, 1, 2) is chosen, and there's only one way to choose indices.