#!/usr/bin/env python3.8
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np
from scipy.sparse.csgraph import dijkstra
from scipy.sparse import csr_matrix

# %%
N, M, L = map(int, readline().split())
T = np.array(readline().split(), np.int64)
ABC = np.array(read().split(), np.int64)
A = ABC[::3] - 1
B = ABC[1::3] - 1
C = ABC[2::3]

# %%
if np.count_nonzero(T > 0) <= 1:
    print(0)
    exit()
# %%
graph = csr_matrix((N, N))
for a, b, c in zip(A, B, C):
    if graph[a, b] == 0 or graph[a, b] > c:
        graph[a, b] = c