import sys

input = sys.stdin.readline

def bellman_ford(edges, N) :
    dist = [0]*(N+1)
    
    for n in range(N) :
        for s,e,t in edges :
            if dist[e] > dist[s] + t :
                dist[e] = dist[s] + t

                if n == N-1:
                    return True
                
    return False

ans = []

for _ in range(int(input())) :
    N, M, W = map(int, input().split())
    edges = []
    
    for _ in range(M) :
        S, E, T = map(int, input().split())
        edges.append((S,E,T))
        edges.append((E,S,T))
    
    for _ in range(W) :
        S, E, T = map(int, input().split())
        edges.append((S,E,-T))
    
    ans.append("YES" if bellman_ford(edges, N) else "NO")

print("\n".join(ans))