#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 1e5 + 10, MAXBIT = 19;
ll n, m, q, cnt = 1, x[MAXN], y[MAXN], s[MAXN], t[MAXN], fen[MAXN];
int h[MAXN], par[MAXN], dp[MAXN][MAXBIT], st[MAXN], ed[MAXN], c[MAXN];
int l[MAXN], r[MAXN];
vector<int> adj[MAXN], q1[MAXN];
pair<int, int> e[MAXN];
vector<pair<int, pair<int, int>>> w;
void input() {
cin >> n >> m >> q;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
adj[--u].push_back(--v);
adj[v].push_back(u);
e[i] = {u, v};
}
for (int i = 0; i < m; i++) {
ll x, w1;
cin >> x >> w1;
--x;
w.push_back({w1, {e[x].first, e[x].second}});
}
for (int i = 0; i < q; i++) {
cin >> s[i] >> t[i] >> x[i] >> y[i];
--s[i];
--t[i];
}
sort(w.begin(), w.end());
}
void calcDp(int u) {
dp[u][0] = par[u];
for (int i = 1; i < MAXBIT; i++)
dp[u][i] = dp[dp[u][i - 1]][i - 1];
}
void dfs1(int u, int p) {
st[u] = cnt++;
par[u] = p;
calcDp(u);
for (auto v : adj[u])
if (v != p) {
h[v] = h[u] + 1;
dfs1(v, u);
}
ed[u] = cnt;
}
int up(int u, int d) {
int res = u;
for (int i = 0; i < MAXBIT; i++)
if ((d >> i) & 1)
res = dp[res][i];
return res;
}
int lca(int u, int v) {
if (h[u] > h[v])
swap(u, v);
v = up(v, h[v] - h[u]);
if (u == v)
return u;
for (int i = MAXBIT - 1; i >= 0; i--)
if (dp[u][i] != dp[v][i]) {
u = dp[u][i];
v = dp[v][i];
}
return par[u];
}
void upd(int u, int x) {
for (; u < MAXN; u += u & -u)
fen[u] += x;
}
ll get(int u) {
ll res = 0;
for (; u; u -= u & -u)
res += fen[u];
return res;
}
void calcAns() {
for (int i = 0; i < q; i++) {
l[i] = -1;
r[i] = m;
}
for (int i = 0; i < MAXBIT; i++) {
for (int j = 0; j < q; j++)
if ((r[j] - l[j]) > 1)
q1[(l[j] + r[j]) / 2].push_back(j);
for (int j = 0; j < m; j++) {
int u = w[j].second.first, v = w[j].second.second;
if (h[u] < h[v])
swap(u, v);
upd(st[u], w[j].first);
upd(ed[u], -w[j].first);
for (auto f : q1[j]) {
int l1 = lca(s[f], t[f]);
ll sum = get(st[s[f]]) + get(st[t[f]]) - 2 * get(st[l1]);
if (sum <= y[f])
l[f] = j;
else
r[f] = j;
}
}
for (int j = 0; j < m; j++)
q1[j].clear();
memset(fen, 0, sizeof(fen));
}
}
void findAns() {
for (int i = 0; i < q; i++)
if (l[i] != -1)
q1[l[i]].push_back(i);
for (int i = 0; i < m; i++) {
int u = w[i].second.first, v = w[i].second.second;
if (h[u] < h[v])
swap(u, v);
upd(st[u], 1);
upd(ed[u], -1);
for (auto f : q1[i]) {
int l1 = lca(s[f], t[f]);
c[f] = get(st[s[f]]) + get(st[t[f]]) - 2 * get(st[l1]);
}
}
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
input();
dfs1(0, 0);
calcAns();
findAns();
for (int i = 0; i < q; i++) {
int sum = get(st[s[i]]) + get(st[t[i]]) - 2 * get(st[lca(s[i], t[i])]) - c[i];
cout << (sum > x[i]? -1: x[i] - sum) << '\n';
}
return 0;
}
