#include <cstdio>
#include <iostream>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <string.h>
#include <string>
#include <vector>
#include <queue>

#define MEM(a,x) memset(a,x,sizeof a)
#define eps 1e-8
#define MOD 10009
#define MAXN 505
#define MAXM 5505
#define INF 99999999
#define ll __int64
#define bug cout<<"here"<<endl
#define fread freopen("ceshi.txt","r",stdin)
#define fwrite freopen("out.txt","w",stdout)

using namespace std;

int n,m,o,num;
struct Path{
    int  u,v,w;
}p[MAXM];
int dis[MAXN];

bool Bellman_Ford(){
    int i,j;
    for(i=1;i<=n;i++) dis[i]=INF;
    dis[1]=0;
    for(i=1;i<=n;i++)
        for(j=0;j<num;j++)
            dis[p[j].u]=min(dis[p[j].u],dis[p[j].v]+p[j].w);
    for(i=0;i<num;i++)
        if(dis[p[i].u]>dis[p[i].v]+p[i].w) return 1;
    return 0;
}

int main(){
    int u,v,w;
    int i,t;
    scanf("%d",&t);
    while(scanf("%d%d%d",&n,&m,&o)!=EOF){

        num=0;

        for(i=0;i<m;i++){
            scanf("%d%d%d",&u,&v,&w);
                p[num].u=u;
                p[num].v=v;
                p[num++].w=w;
                p[num].u=v;
                p[num].v=u;
                p[num++].w=w;
        }
        for(i=0;i<o;i++){
            scanf("%d%d%d",&u,&v,&w);
                p[num].u=u;
                p[num].v=v;
                p[num++].w=-w;

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

        t--;
        if(!t) break;
    }
    return 0;
}