Nick's company employed n people. Now Nick needs to build a tree hierarchy of «supervisor-surbodinate» relations in the company (this is to say that each employee, except one, has exactly one supervisor). There are m applications written in the following form: «employee ai is ready to become a supervisor of employee bi at extra cost ci». The qualification qj of each employee is known, and for each application the following is true: qai > qbi. 

Would you help Nick calculate the minimum cost of such a hierarchy, or find out that it is impossible to build it.

Input

The first input line contains integer n (1 ≤ n ≤ 1000) — amount of employees in the company. The following line contains n space-separated numbers qj (0 ≤ qj ≤ 106)— the employees' qualifications. The following line contains number m (0 ≤ m ≤ 10000) — amount of received applications. The following m lines contain the applications themselves, each of them in the form of three space-separated numbers: ai, bi and ci (1 ≤ ai, bi ≤ n, 0 ≤ ci ≤ 106). Different applications can be similar, i.e. they can come from one and the same employee who offered to become a supervisor of the same person but at a different cost. For each application qai > qbi.

Output

Output the only line — the minimum cost of building such a hierarchy, or -1 if it is impossible to build it.

Examples

Input

4
7 2 3 1
4
1 2 5
2 4 1
3 4 1
1 3 5


Output

11


Input

3
1 2 3
2
3 1 2
3 1 3


Output

-1

Note

In the first sample one of the possible ways for building a hierarchy is to take applications with indexes 1, 2 and 4, which give 11 as the minimum total cost. In the second sample it is impossible to build the required hierarchy, so the answer is -1.
#include <bits/stdc++.h>
using namespace std;
long long read() {
  long long first = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    first = first * 10 + ch - '0';
    ch = getchar();
  }
  return first * f;
}
template <class T>
inline void print(T first) {
  if (first < 0) putchar('-'), first = -first;
  register short a[20] = {}, sz = 0;
  while (first) a[sz++] = first % 10, first /= 10;
  if (sz == 0) putchar('0');
  for (int i = sz - 1; i >= 0; i--) putchar('0' + a[i]);
}
const long long inf = 2147483647;
const long long llinf = 2e18;
const int mod = 998244353;
const unsigned long long MAXMOD = (unsigned long long)mod * (mod - 1);
int n, m;
int fa[1111];
int q[1111];
struct edge {
  int a, b, cost;
  bool operator<(edge ano) const { return cost < ano.cost; }
} ed[11111];
int fp(int first) {
  if (fa[first] == first)
    return first;
  else
    return fa[first] = fp(fa[first]);
}
int main() {
  n = read();
  for (int i = 1; i <= n; i++) q[i] = read();
  m = read();
  for (int i = 1; i <= m; i++) {
    ed[i].a = read(), ed[i].b = read(), ed[i].cost = read();
  }
  for (int i = 1; i <= n; i++) fa[i] = i;
  sort(ed + 1, ed + m + 1);
  long long ans = 0;
  for (int i = 1; i <= m; i++) {
    fp(ed[i].b);
    if (fa[ed[i].b] != ed[i].b) continue;
    ans += ed[i].cost;
    fa[fa[ed[i].b]] = fa[ed[i].a];
  }
  bool ok = 1;
  for (int i = 1; i <= n; i++) {
    fp(i);
    if (i != 1 && fa[i] != fa[i - 1]) ok = 0;
  }
  if (ok)
    print(ans), putchar('\n');
  else
    puts("-1");
  return 0;
}
