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.
import sys
input = sys.stdin.readline
############ ---- Input Functions ---- ############
def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split())) 
	

from typing import List


def minCostCreateHierarchy(n: int, edges) -> int:
    # sort by distance
    # (i, j, d)
    # take third element for sort
    edges.sort(key=lambda x: x[2])

    has_boss = [False for _ in range(n+1)]

    res = 0
    for u, v, d in edges:
        if not has_boss[v]:
            res += d
            has_boss[v] = True
    return res


def task4(n: int, qualifications: List[int],
          statements: List[List[int]]) -> int:
    """
    Parameters:
    :n (int): number of company employees
    :qualifications (list): staff qualifications
    :statements (list): list of statements
    :return: minimum cost of creating a hierarchy
    """
    # qualifications are needed only to state that no cycles exist
    subordinates = set(statement[1] for statement in statements)
    if len(subordinates) != n - 1:
        return -1
    return minCostCreateHierarchy(n, statements)
	
n = inp()
qualifications = inlt()
statements = []
m = inp()
for i in range(m):
    statements.append(inlt())

print(task4(n, qualifications, statements))