#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define F first
#define S second
using namespace std;
const int N = 1e5 + 5;
ll ans;
bool f[N];
int n, P, C, a[N];
vector < ll > s[N];
vector < pair < int , int > > v[N];
int get(int x, ll u) {
int l = 0, r = s[x].size() - 1, mid, res = 0;
while (l <= r) {
mid = (l + r) >> 1;
if (u + s[x][mid] >= 0)
res = s[x].size() - mid, r = mid - 1;
else
l = mid + 1;
}
return res;
}
int find_center(int x, int p, int &cen, int num) {
int tot = 1;
for (int i = 0; i < v[x].size(); ++i) {
int to = v[x][i].F;
if (f[to] || to == p) continue;
tot += find_center(to, x, cen, num);
}
if (cen == -1 && (2 * tot >= num || x == p)) cen = x;
return tot;
}
void fromc(int x, int p, ll recm, ll rec) {
if (recm >= 0) ++ans;
s[P].push_back(recm);
s[C].push_back(recm);
for (int i = 0; i < v[x].size(); ++i) {
ll to = v[x][i].F, cost = a[x] - v[x][i].S;
if (f[to] || to == p) continue;
fromc(to, x, min(recm, rec + cost), rec + cost);
}
}
void ansc(int x, int p, ll recm, ll rec) {
if (recm >= 0) {
ans += get(C, rec) - get(P, rec);
++ans;
}
for (int i = 0; i < v[x].size(); ++i) {
ll to = v[x][i].F, cost = a[to] - v[x][i].S;
if (f[to] || to == p) continue;
ansc(to, x, min(recm + cost, cost), rec + cost);
}
}
void Centroid(int x, int num) {
int cen = -1;
find_center(x, x, cen, num);
f[cen] = true;
C = cen;
for (int i = 0; i < v[cen].size(); ++i) {
ll to = v[cen][i].F, cost = a[cen] - v[cen][i].S; P = to;
if (f[to]) continue;
fromc(to, cen, cost, cost);
sort(s[to].begin(), s[to].end());
}
sort(s[cen].begin(), s[cen].end());
for (int i = 0; i < v[cen].size(); ++i) {
ll to = v[cen][i].F, cost = a[to] - v[cen][i].S; P = to;
if (f[to]) continue;
ansc(to, cen, cost, cost);
}
s[cen].clear();
for (int i = 0; i < v[cen].size(); ++i) {
int to = v[cen][i].F;
if (f[to]) continue;
s[to].clear();
Centroid(to, num / 2);
}
}
main () {
ios::sync_with_stdio(false);
cin.tie(NULL), cout.tie(NULL);
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
}
for (int i = 1; i < n; ++i) {
int a, b, c;
cin >> a >> b >> c;
v[a].pb({b, c});
v[b].pb({a, c});
}
Centroid(1, n);
cout << ans << "\n";
}
