#include<bits/stdc++.h>
//#define int long long
using namespace std;
using ll = long long;
struct Query{
int s, t;
ll gold, silver;
};
const int N = 1e5+5;
int n, m, q, timerDFS, curChain;
int h[N], sz[N];
int tin[N], id[N], par[N], head[N];
int ql[N], qr[N], rem[N];
ll bit[2][N];
Query Q[N];
vector<int> adj[N], md[N];
pair<int,int> E[N], P[N];
void update(int t, int p, ll val){
for(; p <= timerDFS; p += (p & (-p))) bit[t][p] += val;
return;
}
ll get(int t, int p){
ll res = 0;
for(; p; p -= (p & (-p))) res += bit[t][p];
return res;
}
ll get_range(int t, int l, int r){
return get(t, r) - get(t, l-1);
}
void dfs(int x = 1, int p = -1){
sz[x] = 1;
for(int v : adj[x])if(v != p){
par[v] = x;
h[v] = h[x] + 1;
dfs(v, x);
sz[x] += sz[v];
}
return;
}
void decompose(int x = 1, int p = -1){
if(!head[curChain]) head[curChain] = x;
id[x] = curChain;
tin[x] = ++timerDFS;
int nxt = 0; for(int v : adj[x])if(v != p && sz[v] > sz[nxt]) nxt = v;
if(nxt) decompose(nxt, x);
for(int v : adj[x])if(v != p && v != nxt) ++curChain, decompose(v, x);
return;
}
int get_LCA(int u, int v){
while(id[u] != id[v]){
if(id[u] > id[v]) u = par[head[id[u]]];
else v = par[head[id[v]]];
}
return h[u] < h[v] ? u : v;
}
ll get_Path(int u, int v, int type){
int lca = get_LCA(u, v);
ll res = 0;
while(id[u] != id[lca]){
res = res + get_range(type, tin[head[id[u]]], tin[u]);
u = par[head[id[u]]];
}
while(id[v] != id[lca]){
res = res + get_range(type, tin[head[id[v]]], tin[v]);
v = par[head[id[v]]];
}
if(h[u] > h[v]) swap(u, v);
res = res + get_range(type, tin[u]+1, tin[v]);
return res;
}
void solve()
{
cin >> n >> m >> q;
for(int i = 1; i < n; i++){
int u,v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
E[i] = make_pair(u, v);
}
timerDFS = 0, curChain = 0;
dfs(), decompose();
for(int i = 1; i <= m; i++){
int idEdge,C; cin >> idEdge >> C;
P[i] = make_pair((h[E[idEdge].first] < h[E[idEdge].second] ? E[idEdge].second : E[idEdge].first), C);
update(0, tin[P[i].first], 1);
}
sort(P+1, P+1+m, [&](pair<int,int> x, pair<int,int> y){
return x.second < y.second;
});
for(int i = 1; i <= q; i++){
cin >> Q[i].s >> Q[i].t >> Q[i].gold >> Q[i].silver;
ql[i] = -1, qr[i] = m+1;
}
bool changed = true;
while(changed){
changed = false;
for(int i = 1; i <= q; i++){
if(ql[i]+1 < qr[i]){
changed = true;
md[ql[i]+qr[i]>>1].push_back(i);
}
}
for(int i = 0; i <= m; i++){
if(i){
update(0, tin[P[i].first], -1);
update(1, tin[P[i].first], +P[i].second);
}
while(md[i].size()){
int id = md[i].back(); md[i].pop_back();
ll val = get_Path(Q[id].s, Q[id].t, 1);
if(val <= Q[id].silver){
ql[id] = i;
rem[id] = Q[id].gold - get_Path(Q[id].s, Q[id].t, 0);
}
else{
qr[id] = i;
}
}
}
for(int i = 1; i <= m; i++){
update(0, tin[P[i].first], +1);
update(1, tin[P[i].first], -P[i].second);
}
}
for(int i = 1; i <= q; i++){
cout << max(rem[i], -1) <<"\n";
}
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#define name "InvMOD"
if(fopen(name".INP", "r")){
freopen(name".INP", "r", stdin);
freopen(name".OUT", "w", stdout);
}
solve();
return 0;
}
