#include <iostream>
#include <cstdio>
#include <cmath>
#include <queue>
#include <string.h>
using namespace std;

const int INF=0x3f3f3f3f;
;

struct EdgeNode{ int v, w, nxt; };
EdgeNode Edge[maxn*maxn];
bool vis[maxn];
int Head[maxn], Dis[maxn], cnt;
int N, M;
int PushCnt[maxn]; ///记录每一个节点的入队次数、方便判断负环

inline void init()
{
    ; i<=N; i++)
        PushCnt[i] = ,
        Head[i] = -,
        Dis[i]  = INF,
        vis[i]  = false;
    cnt = ;
}

inline void AddEdge(int from, int to, int weight)
{
    Edge[cnt].w = weight;
    Edge[cnt].v = to;
    Edge[cnt].nxt = Head[from];
    Head[from] = cnt++;
}

bool SPFA(int st)///若要判断负环、改为 bool
{
    deque<int> que;
    que.push_back(st);
    vis[st]=true;
    Dis[st]=;
    while (!que.empty())
    {
        int T=que.front(); que.pop_front();
        vis[T]=false;
        ; i=Edge[i].nxt)
        {
            int v=Edge[i].v;
            int w=Edge[i].w;
            if (Dis[v]>Dis[T]+w){
                Dis[v]=Dis[T]+w;
                if (!vis[v]){
                    if(++PushCnt[v] > N) return false; //有负环
                    vis[v]=true;
                    if(!que.empty() && Dis[v] < Dis[que.front()]) que.push_front(v);
                    else que.push_back(v);
                }
            }
        }
    }
    return true;
}

int main(void)
{
    int nCase, W;
    scanf("%d", &nCase);
    while(nCase--){
        scanf("%d %d %d", &N, &M, &W);
        init();
        int from, to, weight;
        ; i<M; i++){
            scanf("%d %d %d", &from, &to, &weight);
            AddEdge(from, to, weight);
            AddEdge(to, from, weight);
        }
        ; i<W; i++){
            scanf("%d %d %d", &from, &to, &weight);
            AddEdge(from, to, -weight);
        }
        SPFA()?puts("NO"):puts("YES");
    }
    ;
}