#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr int MAXN = 1e5 + 7;
constexpr int BASE = 1 << 18;
struct ext{
int lo, hi, mid;
};
vector<pair<int, int>> G[MAXN];
vector<int> mids[MAXN];
pair<int, int> checkpoints[MAXN];
tuple<int, int, int, ll> Queries[MAXN];
pair<ll, int> TREE[BASE << 1];
int queriesLCA[MAXN];
int pre[MAXN], post[MAXN];
int jmp[MAXN][18];
int edges[MAXN];
int depth[MAXN];
int anserw[MAXN];
ext bin[MAXN];
int tajm;
int n, m, q;
void update(int v, pair<ll, int> val){
v += BASE;
TREE[v].first += val.first;
TREE[v].second += val.second;
v/=2;
while(v > 0){
int l = 2*v, r = 2*v+1;
TREE[v].first = TREE[l].first + TREE[r].first;
TREE[v].second = TREE[l].second + TREE[r].second;
v/=2;
}
}
pair<ll, int> query(int a, int b){
a += BASE - 1;
b += BASE + 1;
pair<ll, int> res = {0, 0};
while(a/2 != b/2){
if(a%2 == 0){
res.first += TREE[a+1].first;
res.second += TREE[a+1].second;
}
if(b%2 == 1){
res.first += TREE[b-1].first;
res.second += TREE[b-1].second;
}
a/=2; b/=2;
}
return res;
}
void dfs(int v, int p){
depth[v] = depth[p] + 1;
pre[v] = ++tajm;
jmp[v][0] = p;
for(int k = 1; k <= 17; k++)
jmp[v][k] = jmp[jmp[v][k-1]][k-1];
for(auto [u, id] : G[v]){
if(u == p) continue;
edges[id] = u;
dfs(u, v);
}
post[v] = ++tajm;
}
int lca(int v, int u){
if(depth[u] < depth[v]) swap(u, v);
for(int k = 17; k >= 0; k--)
if(depth[jmp[u][k]] >= depth[v])
u = jmp[u][k];
if(v == u) return v;
for(int k = 17; k >= 0; k--){
if(jmp[u][k] != jmp[v][k]){
u = jmp[u][k];
v = jmp[v][k];
}
}
return jmp[v][0];
}
void treeclear(){
for(int i = 0; i < (BASE << 1); i++)
TREE[i] = {0, 0};
}
bool check(tuple<int, int, int, ll> a, int v){
auto [s, t, x, y] = a;
if(depth[t] < depth[s]) swap(s, t);
pair<ll, int> res = query(pre[queriesLCA[v]], pre[t]);
if(queriesLCA[v] != s){
pair<ll, int> xd = query(pre[queriesLCA[v]], pre[s]);
res.first += xd.first;
res.second += xd.second;
}
if(res.first > y) return true;
return false;
}
void parallel_solve(){
int zostalo = q;
while(zostalo){
for(int i = 0; i <= m; i++){
update(pre[edges[checkpoints[i].second]], {checkpoints[i].first, 1});
update(post[edges[checkpoints[i].second]], {-checkpoints[i].first, -1});
for(auto candidate : mids[i]){
if(check(Queries[candidate], candidate)) bin[candidate].hi = i;
else bin[candidate].lo = i + 1;
bin[candidate].mid = (bin[candidate].lo + bin[candidate].hi)/2;
if(bin[candidate].lo == bin[candidate].hi) zostalo--;
else mids[bin[candidate].mid].push_back(candidate);
}
mids[i].clear();
mids[i].shrink_to_fit();
}
treeclear();
}
}
void save_res(int v, bool save){
auto [s, t, x, y] = Queries[v];
if(depth[t] < depth[s]) swap(s, t);
pair<ll, int> res = query(pre[queriesLCA[v]], pre[t]);
if(queriesLCA[v] != s){
pair<ll, int> xd = query(pre[queriesLCA[v]], pre[s]);
res.first += xd.first;
res.second += xd.second;
}
if(save){
anserw[v] = res.second;
if(res.first > y) anserw[v] = max(anserw[v]-1, 0);
}
else anserw[v] = x - max(0, res.second - anserw[v]);
}
void solve(){
for(int i = 1; i <= q; i++)
mids[bin[i].lo].push_back(i);
for(int i = 1; i <= m; i++){
update(pre[edges[checkpoints[i].second]], {checkpoints[i].first, 1});
update(post[edges[checkpoints[i].second]], {-checkpoints[i].first, -1});
for(auto candidate : mids[i])
save_res(candidate, 1);
mids[i].clear();
mids[i].shrink_to_fit();
}
for(int i = 1; i <= q; i++)
save_res(i, 0);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> q;
for(int i = 1; i < n; i++){
int a, b;
cin >> a >> b;
G[a].push_back({b, i});
G[b].push_back({a, i});
}
for(int i = 1; i <= m; i++){
int p, c;
cin >> p >> c;
checkpoints[i] = {c, p};
}
dfs(1, 1);
for(int i = 1; i <= q; i++){
int s, t, x;
ll y;
cin >> s >> t >> x >> y;
Queries[i] = {s, t, x, y};
queriesLCA[i] = lca(s, t);
bin[i].lo = 0;
bin[i].hi = m;
bin[i].mid = (0+m)/2;
mids[bin[i].mid].push_back(i);
}
sort(checkpoints + 1, checkpoints + 1 + m);
parallel_solve();
solve();
for(int i = 1; i <= q; i++)
cout << max(anserw[i], -1) << "\n";
}
