// OBI 2014 - 2nd Stage - Mapa
// Lúcio Cardoso

#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e5+10;

int pai[maxn], peso[maxn];

bool mark[maxn];

int Find(int x)
{
	if (pai[x] == x) return x;
	return pai[x] = Find(pai[x]);
}

void Join(int x, int y)
{
	x = Find(x), y = Find(y);
	if (x == y) return;

	if (peso[x] < peso[y]) swap(x, y);

	pai[y] = x, peso[x] += peso[y];
}

int main(void)
{
	int n;
	scanf("%d", &n);

	for (int i = 1; i <= n; i++)
		pai[i] = i, peso[i] = 1;

	for (int i = 1; i < n; i++)
	{
		int u, v, w;
		scanf("%d %d %d", &u, &v, &w);

		if (!w) Join(u, v);
	}

	vector<int> comp;

	for (int i = 1; i <= n; i++)
	{
		if (!mark[Find(i)])
		{
			mark[Find(i)] = true;
			comp.push_back(peso[Find(i)]);
		}
	}

	int tot = n;
	long long ans = 0;

	for (auto c: comp)
	{
		ans += 1ll*c*(tot-c);
		tot -= c;
	}

	printf("%lld\n", ans);
}