## https://yukicoder.me/problems/no/2477

MAX_INT = 10 ** 18

def main():
    N, M = map(int, input().split())
    next_nodes = [[] for _ in range(N)]
    for _ in range(M):
        u, v, w = map(int, input().split())
        next_nodes[u - 1].append((v - 1, w))

    K = int(input())
    state_base_map = {}
    for _ in range(K):
        a, b, c = map(int, input().split())
        a -= 1
        b -= 1
        c -= 1
        state_base_map[(a, b, c)] = MAX_INT

    dp = [[MAX_INT, MAX_INT] for _ in range(N)]
    prev = [[-2, -2] for _ in range(N)]
    dp[0][0] = 0
    prev[0][0] = -1
    for s_n in range(N):
        for idx in range(2):
            cost = dp[s_n][idx]
            prev_n = prev[s_n][idx]
            for next_n, w in next_nodes[s_n]:
                if (prev_n, s_n, next_n) in state_base_map:
                    continue

                new_cost = w + cost

                if dp[next_n][0] > new_cost:
                    dp[next_n][1] = dp[next_n][0]
                    dp[next_n][0] = new_cost
                    prev[next_n][1] = prev[next_n][0]
                    prev[next_n][0] = s_n
                elif dp[next_n][1] > new_cost:
                    dp[next_n][1] = new_cost
                    prev[next_n][1] = s_n
    
    
    answer = MAX_INT
    for cost in dp[-1]:
        answer = min(answer, cost)
    if answer == MAX_INT:
        print(-1)
    else:
        print(answer)




    





if __name__ == "__main__":
    main()