void dfs(int u)

{

    cir[u] = 1;

    for(int i = id[u];~i;i = edge[i].pre)

    {

        if(!cir[edge[i].to])

            dfs(edge[i].to);

    }

}

/*

spfa负环的判断

*/

#include <iostream>

#include <cstdio>

#include <string.h>

#include <queue>

#include <algorithm>

#define inf (1 << 29)

using namespace std;

typedef long long ll;

const int maxn = 600;

const int maxm = 3e3;

int id[maxn],cnt;

struct node{

    int to,cost,pre;

}e[maxm * 2];

int dis[maxn];

int vis[maxn];

int time[maxn];

queue<int> q;

void init()

{

    while(q.size())q.pop();

    memset(time,0,sizeof(time));

    memset(vis,0,sizeof(vis));

    memset(id,-1,sizeof(id));

    cnt = 0;

}

void add(int from,int to,int cost)

{

    e[cnt].to = to;

    e[cnt].cost = cost;

    e[cnt].pre = id[from];

    id[from] = cnt++;

}

int spfa(int s,int n)

{

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

        dis[i] = inf;

    q.push(s);

    vis[s] = 1;

    time[s] = 1;

    dis[s] = 0;

    while(q.size())

    {

        int now = q.front();

        q.pop();

        vis[now] = 0;

        for(int i = id[now];~i;i = e[i].pre)

        {

            int to = e[i].to;

            int cost = e[i].cost;

            if(dis[to] > dis[now] + cost)

            {

                dis[to] = dis[now] + cost;

                if(!vis[to])

                {

                    vis[to] = 1;

                    q.push(to);

                    if(++time[to] > n)

                        return 0;

                }

            }

        }

    }

    return 1;

}

int main()

{

    int t;

    scanf("%d",&t);

    while(t--)

    {

        int n,m,k;

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

        init();

        int a,b,x;

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

        {

            scanf("%d%d%d",&a,&b,&x);

            add(a,b,x);

            add(b,a,x);

        }

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

        {

            scanf("%d%d%d",&a,&b,&x);

            add(a,b,-x);

        }

        int op = spfa(1,n);

        if(op)

            printf("NO\n");

        else

            printf("YES\n");

    }

    return 0;

}