#include <bits/stdc++.h>
using namespace std;
struct Edge {
  int u;
  int v;
  int w;
  Edge() { u = v = w = -1; }
  Edge(int a, int b, int c) : u(a), v(b), w(c) {}
};
int N, M, qa, qb, qc;
vector<pair<int, int> > adj[1000 + 5];
bool vis[1000 + 5];
int D[1000 + 5];
int PAR[1000 + 5];
int ST[1000 + 5];
int stIdx;
vector<Edge> Edges;
bool hasIn[1000 + 5];
int inWeight[1000 + 5];
void dfs(int v) {
  vis[v] = true;
  const vector<pair<int, int> >& adjVec = adj[v];
  int len = (int)adjVec.size();
  int nextV;
  for (int i = 0; i < len; i++) {
    nextV = adjVec[i].first;
    if (!vis[nextV]) {
      dfs(nextV);
    }
  }
  ST[stIdx++] = v;
}
int dfsTwo(int v) {
  vis[v] = true;
  int sum = 1, nextV;
  const vector<pair<int, int> >& adjVec = adj[v];
  int len = (int)adjVec.size();
  for (int i = 0; i < len; i++) {
    nextV = adjVec[i].first;
    if (!vis[nextV]) {
      sum += dfsTwo(nextV);
    }
  }
  return sum;
}
int main() {
  int tmpInt = 0, root = 0, v, d, nextV, nextD, len, cost;
  scanf("%d", &N);
  for (int i = 0; i < N; i++) {
    scanf("%d", &tmpInt);
  }
  scanf("%d", &M);
  for (int i = 0; i < M; i++) {
    scanf("%d %d %d", &qa, &qb, &qc);
    adj[qa].push_back(pair<int, int>(qb, qc));
    Edges.push_back(Edge(qa, qb, qc));
  }
  for (int i = 1; i <= N; i++) {
    if (!vis[i]) {
      dfs(i);
    }
  }
  root = ST[stIdx - 1];
  memset(vis, 0, sizeof(vis));
  if (N != dfsTwo(root)) {
    printf("-1\n");
  } else {
    cost = 0;
    for (int i = 0; i < M; i++) {
      const Edge& edge = Edges[i];
      v = edge.v;
      if (!hasIn[v]) {
        hasIn[v] = true;
        inWeight[v] = edge.w;
        cost += edge.w;
      } else if (edge.w < inWeight[v]) {
        cost = cost - inWeight[v] + edge.w;
        inWeight[v] = edge.w;
      }
    }
    printf("%d\n", cost);
  }
  return 0;
}
