import java.util.*;

class Node {
    int u, v, w;

    Node(int u, int v, int w) {
        this.u = u;
        this.v = v;
        this.w = w;
    }
}

class _1865 {

    static boolean bellman_ford(Node[] edges, Node info) {
        int N = info.u;
        int M = info.v;
        int W = info.w;
        
        int[] distance = new int[N+1];
        Arrays.fill(distance, 0);

        for(int n=0; n<N; n++) {
            for(int i=0; i<2*M+W; i++) {
                int current = edges[i].u;
                int next = edges[i].v;
                int time = edges[i].w;

                if(distance[next] > distance[current] + time) {
                    if(n==N-1) return true;

                    distance[next] = distance[current] + time;
                }
            }
        }

        return false;
    }

    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        int T = sc.nextInt();
        
        for(int t=0; t<T; t++) {
            int N = sc.nextInt();
            int M = sc.nextInt();
            int W = sc.nextInt();
            Node info = new Node(N, M, W);

            Node[] edges = new Node[2*M+W];

            for(int i=0; i<2*M; i+=2) {
                int u = sc.nextInt();
                int v = sc.nextInt();
                int w = sc.nextInt();

                edges[i] = new Node(u, v, w);
                edges[i+1] = new Node(v, u, w);
            }

            for(int i=0; i<W; i++) {
                int u = sc.nextInt();
                int v = sc.nextInt();
                int w = sc.nextInt();

                edges[2*M+i] = new Node(u, v, (-1)*w);
            }

            boolean negative_cycle = bellman_ford(edges, info);

            System.out.println(negative_cycle ? "YES" : "NO");
        }

        sc.close();
    }
}