#include<iostream>

#include<cstdio>

#include<queue>

#include<vector>

#include<cstring>

#include<algorithm>

using namespace std;

const int INF=10e7;

const int MAXN=510;

int f,n,m,w,s,e,t;

int lc[MAXN],cntNode[MAXN];

bool vis[MAXN];

struct edge

{

    int v,cost;

}E;

vector<edge> Edge[MAXN];

bool SPFA()

{

    queue<int> que;

    int u,v,c,len;

    for(int i=1;i<=n;i++)

        lc[i]=INF,vis[i]=0,cntNode[i]=0;

    lc[1]=0;vis[1]=1;cntNode[1]=1;

    que.push(1);

    while(!que.empty())

    {

        u=que.front();que.pop();

        vis[u]=0;len=Edge[u].size();

        for(int i=0;i<len;i++)

        {

            v=Edge[u][i].v;

            c=Edge[u][i].cost;

            if(lc[v]>lc[u]+c)

            {

                lc[v]=lc[u]+c;

                if(!vis[v])

                {

                    vis[v]=1;

                    ++cntNode[v];

                    que.push(v);

                    if(cntNode[v]>n)

                        return true;

                }

            }

        }

    }

    return false;

}

int main()

{

    scanf("%d",&f);

    while(f--)

    {

        scanf("%d%d%d",&n,&m,&w);

        for(int i=1;i<=n;i++)

            Edge[i].clear();

        while(m--)

        {

            scanf("%d%d%d",&s,&e,&t);

            E.v=e;E.cost=t;

            Edge[s].push_back(E);

            E.v=s;E.cost=t;

            Edge[e].push_back(E);

        }

        while(w--)

        {

            scanf("%d%d%d",&s,&e,&t);

            E.v=e;E.cost=-t;

            Edge[s].push_back(E);

        }

        if(SPFA()) printf("YES\n");

        else printf("NO\n");

    }

    return 0;

}