#include <iostream>
#include <cmath>

using namespace std;

int main() {
	int n, a[110], ans = 0;
	cin >> n;
	for (int i = 1; i <= n; i++)
		cin >> a[i];
	for (int i = 3; i <= n; i++)
		for (int j = 1; j <= i - 2; j++)
			for (int k = j + 1; k <= i - 1; k++) {
				if (a[j] == a[k])
					continue;
				if (a[i] == a[j] + a[k])
					ans++;
			}
	cout << ans;
	return 0;
}