// Thuy Ttienn
// 14 ngày trước khi tới sinh nhật Tiên 24/7.
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define Sz(x) ((int) (x).size())
#define file(name) if (fopen(name".inp", "r")) {freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);}
#define TIME 1.0 * clock() / CLOCKS_PER_SEC
template <typename T1, typename T2> bool mini(T1 &a, T2 b) {if (a > b) a = b; else return 0; return 1;}
template <typename T1, typename T2> bool maxi(T1 &a, T2 b) {if (a < b) a = b; else return 0; return 1;}
const int inf = 2e9 + 7;
const int mod = 1e9 + 7;
const int N = 1e5 + 5;
int n, m, q;
vector <int> a[N];
pair <int, int> edge[N];
vector <pair <int, int>> c;
int s[N], t[N], gold[N];
ll silver[N];
int l[N], r[N], num[N];
int st[2 * N], tour[2 * N], h[N], tourDfs = 0;
int LCA[20][2 * N];
int stId[N], edId[N], idDfs = 0;
vector <int> query[N];
int res[N];
void dfs(int u, int pre) {
tour[++tourDfs] = u;
st[u] = tourDfs;
stId[u] = ++idDfs;
for (int v: a[u]) if (v != pre) {
h[v] = h[u] + 1;
dfs(v, u);
tour[++tourDfs] = u;
}
edId[u] = idDfs;
}
#define Min(a, b) ((h[a] < h[b]) ? a : b)
void prepare_lca() {
for (int i = 1; i <= tourDfs; i++) LCA[0][i] = tour[i];
for (int lg = 1; (1 << lg) <= tourDfs; lg++)
for (int i = 1; i + (1 << lg) - 1 <= tourDfs; i++)
LCA[lg][i] = Min(LCA[lg - 1][i], LCA[lg - 1][i + (1 << (lg - 1))]);
}
int lca(int u, int v) {
if (st[u] > st[v]) swap(u, v);
int lg = 31 - __builtin_clz(st[v] - st[u] + 1);
return Min(LCA[lg][st[u]], LCA[lg][st[v] - (1 << lg) + 1]);
}
struct Fenwick_tree {
ll BIT[N];
void reset() {
memset(BIT, 0, sizeof(BIT));
}
void update(int k, ll val) {
for (; k <= n; k += k & (-k)) BIT[k] += val;
}
void update_node(int u, ll val) {
update(stId[u], val);
update(edId[u] + 1, -val);
}
ll get(int k) {
ll res = 0;
for (; k >= 1; k -= k & (-k)) res += BIT[k];
return res;
}
ll get(int l, int r) {
if (l > r) return 0;
return get(r) - get(l - 1);
}
ll get_path(int u, int v) {
int Lca = lca(u, v);
return get(stId[Lca] + 1, stId[u]) + get(stId[Lca] + 1, stId[v]);
}
} allStation, numStation, valStation;
bool check(int id) {
return valStation.get_path(s[id], t[id]) <= silver[id];
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
file("");
cin >> n >> m >> q;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
a[u].push_back(v);
a[v].push_back(u);
edge[i] = {u, v};
}
dfs(1, 1);
prepare_lca();
c.push_back({-1, -1});
for (int i = 1; i <= m; i++) {
int pos, coin; cin >> pos >> coin;
pair <int, int> e = edge[pos];
int u = e.first, v = e.second;
if (stId[u] > stId[v]) swap(u, v);
c.push_back({coin, v});
}
sort(c.begin(), c.end());
for (int i = 1; i <= q; i++) cin >> s[i] >> t[i] >> gold[i] >> silver[i];
for (int i = 1; i <= q; i++) {
l[i] = 0;
r[i] = m;
}
while (true) {
for (int i = 0; i <= m; i++) query[i].clear();
numStation.reset();
valStation.reset();
bool checker = false;
for (int i = 1; i <= q; i++) if (l[i] <= r[i]) {
query[(l[i] + r[i]) / 2].push_back(i);
checker = true;
}
if (!checker) break;
for (int i = 0; i <= m; i++) {
if (i) {
int u = c[i].second, val = c[i].first;
numStation.update_node(u, 1);
valStation.update_node(u, val);
}
for (int x: query[i])
if (check(x)) {
l[x] = i + 1;
num[x] = numStation.get_path(s[x], t[x]);
}
else r[x] = i - 1;
}
}
for (int i = 1; i <= m; i++) allStation.update_node(c[i].second, 1);
for (int i = 1; i <= q; i++) {
int x = allStation.get_path(s[i], t[i]) - num[i];
res[i] = ((gold[i] >= x) ? gold[i] - x : -1);
}
for (int i = 1; i <= q; i++) cout << res[i] << "\n";
cerr << "Time elapsed: " << TIME << "s.\n";
return 0;
}
