#include<stdio.h>
#include<string.h>
#include<stdbool.h>

#define N 510
#define M 5210

int f;
int n, m, w;
int s, e, t;
int dist[N];
int count[N];
int h[N], cnt;
int que[N], head, tail;
bool inQue[N];

struct edge{
    int to;
    int next;
    int time;
}E[M];

void add(int v, int w, int time){
    E[++cnt].next = h[v];
    E[cnt].to = w;
    E[cnt].time = time;
    h[v] = cnt;
}

bool spfa(){
    memset(dist, 0, sizeof dist);
    memset(inQue, 0, sizeof inQue);
    memset(count, 0, sizeof count);
    head = 0, tail = 0;
    for(int i = 1; i <= n; i++){
        que[++tail] = i;
        inQue[i] = true;
    }

    while(head != tail){
        int t = que[++head];
        head %= N;
        inQue[t] = false;

        for(int i = h[t]; i != -1; i = E[i].next){
            int j = E[i].to;
            if(dist[j] > dist[t] + E[i].time){
                dist[j] = dist[t] + E[i].time;
                count[j] = count[t] + 1;

                if(count[j] >= n)  return true;
                if(!inQue[j]){
                    que[++tail] = j;
                    tail %= N;
                    inQue[j] = true;
                }
            }
        }
    }
    return false;
}


int main(){

    scanf("%d", &f);

    while(f--){
        scanf("%d %d %d", &n, &m, &w);
        memset(h, -1, sizeof h);
        cnt = 0;

        for(int i = 1; i <= m; i++){
            int a, b, t;
            scanf("%d %d %d", &a, &b, &t);
            add(a, b, t), add(b, a, t);
        }

        for(int i = 1; i <= w; i++){
            int a, b, t;
            scanf("%d %d %d", &a, &b, &t);
            add(a, b, -t);
        }

        if(spfa())  printf("YES\n");
        else printf("NO\n");
    }

    return 0;
}