#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<queue>using namespace std;#define INF 100000000int u[6000],v[6000],w[6000];int first[6000],next[6000];int coun[6000];__int64 d[6000];int main(){    int f,n,m,ww,s,e,t;    int i,j,k;    scanf("%d",&f);    while(f--)    {        scanf("%d%d%d",&n,&m,&ww);        memset(first,-1,sizeof(first));        memset(coun,0,sizeof(coun));        int ok=0;        for(i=1;i<=2*m;i+=2)        {            scanf("%d%d%d",&s,&e,&t);            u[i]=s;  v[i]=e;  w[i]=t;            u[i+1]=e;v[i+1]=s;w[i+1]=t;            next[i]=first[u[i]];            first[u[i]]=i;            next[i+1]=first[u[i+1]];            first[u[i+1]]=i+1;        }        for(i=2*m+1;i<=2*m+ww;i++)        {            scanf("%d%d%d",&s,&e,&t);            u[i]=s;v[i]=e;w[i]=-t;            next[i]=first[u[i]];            first[u[i]]=i;        }        //queue<int> q;        int tot[6000];        int cnt=0;        bool inq[6000];        for(i=0;i<=n;i++) d[i]=INF;        d[1]=0;        memset(inq,0,sizeof(inq));        //q.push(1);        tot[cnt++]=1;        coun[1]++;        //while(!q.empty())        while(cnt)        {            if(ok==1) break;            //int x=q.front();q.pop();            int x=tot[--cnt];            inq[x]=false;            for(int e=first[x];e!=-1;e=next[e])            {                if(d[v[e]]>d[x]+w[e])                {                    d[v[e]]=d[x]+w[e];                    if(!inq[v[e]])                    {                        inq[v[e]]=true;                        //q.push(v[e]);                        tot[cnt++]=v[e];                        coun[v[e]]++;                        if(coun[v[e]]>n) {ok=1;break;}                    }                }            }        }        if(ok==1) printf("YES\n");        else printf("NO\n");    }    return 0;}