import collections

import sys

tc = int(input())

answer = []

for _ in range(tc):

n, m, w = map(int,sys.stdin.readline().split())

edges = []

inf_cycle = True

dist = [500000]*(n+1)

dist[1] = 0

for _ in range(m):

s, e, t = map(int, sys.stdin.readline().split())

edges.append([s, e, t])

edges.append([e, s, t])

for _ in range(w):

s, e, t =map(int,sys.stdin.readline().split())

edges.append([s,e,t*-1])

for i in range(n):

for s,e,t in edges:

if dist[e] > dist[s] + t:

if i == n-1:

inf_cycle=False

break

dist[e] = dist[s] +t

if inf_cycle ==False:

answer.append('YES')

else:

answer.append('NO')

for ele in answer:

print(ele)