#include <bits/stdc++.h>
using namespace std;
#define fr first
#define sc second
using ll = long long;
#define int ll
const int N = 100005;
vector<pair<int, int>> vec[N];
int a[N], sz[N];
bool is_centr[N];
ll rasp = 0;
vector<int> de_la_mine, pana_la_mine;
/*
pana_sus este cat imi mai trebuie ca sa ajung din mine pana in c
sum_sus = suma de petrol pana la c exclusiv (inclusiv eu) - suma drumurilor
cat_jos = cat petrol imi trebuie ca sa ajung pana in eu inclusiv
petrol_jos = cu cat petrol ajung pana in mine in acest caz minimal
*/
void dfs(int nod, int papa, int pana_sus, int sum_sus, int cat_jos, int petrol_jos) {
if (pana_sus == 0) {
de_la_mine.push_back(sum_sus);
} else {
de_la_mine.push_back(-1);
}
pana_la_mine.push_back(cat_jos);
for (auto i : vec[nod]) {
if (i.fr == papa || is_centr[i.fr]) {
continue;
}
int n_pana_sus = max(0ll, pana_sus + i.sc - a[i.fr]);
int n_sum_sus = sum_sus + a[i.fr] - i.sc;
int n_cat_jos = cat_jos + max(0ll, i.sc - petrol_jos - a[nod]);
int n_petrol_jos = max(0ll, petrol_jos + a[nod] - i.sc);
dfs(i.fr, nod, n_pana_sus, n_sum_sus, n_cat_jos, n_petrol_jos);
}
}
ll solve(vector<int> dlmn, vector<int> plmn) {
ll ans = 0;
sort(dlmn.begin(), dlmn.end());
sort(plmn.begin(), plmn.end());
// cout << "dlmn: ";
// for (auto i : dlmn) {
// cout << i << " ";
// }
// cout << '\n';
// cout << "plmn: ";
// for (auto j : plmn) {
// cout << j << " ";
// }
// cout << '\n';
int nr1 = dlmn.size();
int p = 0;
for (auto i : plmn) {
while (p < dlmn.size() && dlmn[p] < i) {
nr1 --;
p ++;
}
ans += nr1;
}
// cout << "Ans: ";
// cout << ans << '\n';
return ans;
}
int find_centr(int nod, int papa, int target) {
for (auto i : vec[nod]) {
if (i.fr != papa && !is_centr[i.fr] && sz[i.fr] >= target) {
return find_centr(i.fr, nod, target);
}
}
return nod;
}
void dfs_sz(int nod, int papa) {
sz[nod] = 1;
for (auto i : vec[nod]) {
if (i.fr != papa && !is_centr[i.fr]) {
dfs_sz(i.fr, nod);
sz[nod] += sz[i.fr];
}
}
}
/*
pana_sus este cat imi mai trebuie ca sa ajung din mine pana in c
sum_sus = suma de petrol pana la c exclusiv (inclusiv eu) - suma drumurilor
cat_jos = cat petrol imi trebuie ca sa ajung pana in eu inclusiv
petrol_jos = cu cat petrol ajung pana in mine in acest caz minimal
*/
void decomp(int lol) {
dfs_sz(lol, 0);
int c = find_centr(lol, 0, (sz[lol] + 1) / 2);
is_centr[c] = 1;
vector<int> take_in, take_out;
//cout << c << '\n';
take_in = {0};
take_out = {0};
ll ans = 0;
for (auto i : vec[c]) {
if (is_centr[i.fr]) {
continue;
}
de_la_mine.clear();
pana_la_mine.clear();
dfs(i.fr, c, max(0ll, i.sc - a[i.fr]), a[i.fr] - i.sc, max(0ll, i.sc - a[c]), max(0ll, a[c] - i.sc));
for (auto j : de_la_mine)
take_in.push_back(j);
for (auto j : pana_la_mine)
take_out.push_back(j);
ans += solve(de_la_mine, pana_la_mine);
}
ans = solve(take_in, take_out) - ans - 1;
rasp += ans;
// cout << c << " " << ans << '\n';
for (auto i : vec[c]) {
if (!is_centr[i.fr]) {
decomp(i.fr);
}
}
}
signed main() {
int n;
cin >> n;
for (int i = 1; i <= n; i ++) {
cin >> a[i];
}
for (int i = 1; i < n; i ++) {
int u, v, w;
cin >> u >> v >> w;
vec[u].push_back({v, w});
vec[v].push_back({u, w});
}
decomp(1);
cout << rasp << '\n';
}
/*
de_la_mine[x] = daca nu ajungi pana la c -1, altfel cu cata benzina ajungi in c
pana_la_mine[x] = cata benzina imi trebuie sa ajung pana in x daca incep cu rezervorul plin cu ce am in c
*/
