#include<bits/stdc++.h>
using namespace std;
const int N = 1e7+5;
vector<int> adj[N];
int strength[N];
bool visited[N];
int parent[N];
int flag = 1;
void bfs(int node)
{
queue<int> q;
q.push(node);
parent[node] = -1;
while(!q.empty()){
int cur_node = q.front();
q.pop();
if(strength[cur_node] == 0)
continue;
for(auto next_node : adj[cur_node]){
if(next_node == parent[cur_node])
continue;
if(!visited[next_node]){
visited[next_node] = true;
strength[next_node] = strength[cur_node] - 1;
parent[next_node] = cur_node;
q.push(next_node);
}
else if(strength[next_node] != strength[cur_node] - 1 && parent[cur_node] != parent[next_node]){
flag = 0;
return;
}
}
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int t;
cin >> t;
while(t--){
flag = 1;
memset(visited,false,sizeof(visited));
int n,r,m;
cin >> n >> r >> m;
for(int i = 0; i < N;i++){
adj[i].clear();
}
for(int i = 0; i < r;i++){
int u,v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
memset(strength,-1,sizeof(strength));
for(int i = 0; i < m;i++){
int k,s;
cin >> k >> s;
if(visited[k])
flag = 0;
strength[k] = s;
visited[k] = true;
if(flag)
bfs(k);
}
for(int i = 1; i <= n;i++){
if(visited[i] == -1)
flag = 0;
}
if(flag)
puts("Yes");
else
puts("No");
}
}
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