#include <bits/stdc++.h>

using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()

template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
  out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
  for(T& x: vec) {is >> x;} return is;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
  out<<'['; for(T i: a) {out<<i<<',';} out<<']'; return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

struct UnionFind {
  vector<int> par, s;
  UnionFind(int n=2e5) { init(n); }
  void init(int n) { 
    s.assign(n, 1); par.resize(n); 
    iota(par.begin(), par.end(), 0);
  }
  int find(int x) {
    if(par[x] == x) return x;
    return par[x] = find(par[x]);
  }
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if(x == y) return;
    if(s[x] < s[y]) par[x] = y, s[y] = s[x] + s[y];
    else par[y] = x, s[x] = s[x] + s[y];
  }
  bool same(int x, int y) { return find(x) == find(y); }
  int size(int x) { return s[find(x)]; }
};

template<bool istree = true>
ll voronoiMst(vector<vector<PII>> g) {
  const ll n = g.size();
  ll ret = 0;
  vector<pair<ll,PII>> edges; 
  vector<ll> dist(n, LLINF), col(n, -1);
  struct node {
    ll dist, vertex, col;
    node() {}
    node(ll a, ll b, ll c) : dist(a), vertex(b), col(c) {}
    bool operator<(node nd) const { return dist > nd.dist; }
  };
  priority_queue<node> que;
  REP(i, n/2) que.push(node(0, i, i)); // 初期化に注意!!!
  while(que.size()) {
    node p = que.top(); que.pop();
    if(dist[p.vertex] == LLINF) {
      dist[p.vertex] = p.dist;
      col[p.vertex] = p.col;
      for(auto to: g[p.vertex]) {
        que.push(node(p.dist+to.second, to.first, p.col));
      }
    } else {
      if(p.col != col[p.vertex]) {
        if(istree) ret += dist[p.vertex] + p.dist;
        else edges.push_back({dist[p.vertex]+p.dist, {col[p.vertex], p.col}});
      }
    }
  }
  if(istree) return ret/2;
  sort(ALL(edges));
  // cout << edges << endl;
  UnionFind uf(2*n);
  REP(i, edges.size()) {
    if(uf.same(edges[i].second.first, edges[i].second.second)) continue;
    uf.unite(edges[i].second.first, edges[i].second.second);
    ret += edges[i].first;
  }
  return ret;
}

// こどふぇす tree mst
signed main(void) 
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  ll n;
  cin >> n;
  vector<vector<PII>> g(2*n);
  REP(i, n) {
    ll x;
    cin >> x;
    g[i].push_back({i+n, x});
    g[i+n].push_back({i, x});
  }
  REP(i, n-1) {
    ll a, b, c;
    cin >> a >> b >> c;
    a--, b--;
    g[a+n].push_back({b+n, c});
    g[b+n].push_back({a+n, c});
  }

  cout << voronoiMst<false>(g) << endl;

  return 0;
}

Measured memory_bytes: 102500