#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using pint = pair <int, int>;
const int mxN = 100005, SIZE = 200000;
vector <int> adj[mxN], mid[mxN];
int n, m, q, A[mxN], B[mxN], S[mxN], T[mxN], X[mxN], ans[mxN]; LL Y[mxN];
int tin[2 * mxN], tout[2 * mxN], tcnt = 0, low[mxN], high[mxN], L[mxN];
pint C[mxN];
struct lca {
int par[20][mxN], dep[mxN];
void dfs(int now, int p){
par[0][now] = p;
for (int chi : adj[now]){
if (chi == p) continue;
dep[chi] = dep[now] + 1;
dfs(chi, now);
}
}
void init(){
dfs(1, 1);
for (int i = 1; i < 20; i++){
for (int j = 1; j <= n; j++){
par[i][j] = par[i - 1][par[i - 1][j]];
}
}
}
int query(int x, int y){
if (dep[x] < dep[y]) swap(x, y);
int dif = dep[x] - dep[y];
for (int i = 0; dif; i++){
if (dif & 1) x = par[i][x];
dif /= 2;
}
for (int i = 19; i >= 0; i--){
if (par[i][x] != par[i][y]){
x = par[i][x], y = par[i][y];
}
}
if (x == y) return x;
else return par[0][x];
}
} lca;
struct segtree {
LL node[8 * mxN];
void init(){
memset(node, 0, sizeof node);
}
void update(int x, int val){
for (x += 2 * n; x > 0; x /= 2) node[x] += val;
}
LL query(int L, int R){
LL ret = 0;
for (L += 2 * n, R += 2 * n; L <= R; L /= 2, R /= 2){
if (L % 2 == 1) ret += node[L++];
if (R % 2 == 0) ret += node[R--];
}
return ret;
}
} tree1, tree2;
void euler_tour(int now, int p)
{
tin[now] = ++tcnt;
for (int elm : adj[now]){
if (elm == p) continue;
euler_tour(elm, now);
}
tout[now] = ++tcnt;
}
int main()
{
scanf("%d %d %d", &n, &m, &q);
for (int i = 1; i <= n - 1; i++){
scanf("%d %d", &A[i], &B[i]);
adj[A[i]].push_back(B[i]);
adj[B[i]].push_back(A[i]);
}
for (int i = 1; i <= m; i++) scanf("%d %d", &C[i].second, &C[i].first);
for (int i = 1; i <= q; i++) scanf("%d %d %d %lld", &S[i], &T[i], &X[i], &Y[i]);
lca.init();
euler_tour(1, 1);
sort(C + 1, C + m + 1); // {silver no, road no}
for (int i = 1; i <= q; i++){low[i] = 0, high[i] = m;}
for (int i = 1; i <= q; i++){
L[i] = lca.query(S[i], T[i]);
}
for (int i = 1; i <= n - 1; i++){
if (lca.dep[A[i]] < lca.dep[B[i]]) swap(A[i], B[i]);
}
memset(ans, -1, sizeof ans);
while (1){
tree1.init();
tree2.init();
for (int i = 0; i <= m; i++) mid[i].clear();
bool endflag = true;
for (int i = 1; i <= q; i++){
if (low[i] <= high[i]){
endflag = false;
mid[(low[i] + high[i]) / 2].push_back(i);
}
}
if (endflag) break;
for (int i = 0; i <= m; i++){
for (int j : mid[i]){ // ansi = maximum no of gold replaced by silver
LL ysum = tree2.query(1, tin[T[j]]) + tree2.query(1, tin[S[j]]) - 2 * tree2.query(1, tin[L[j]]);
if (ysum <= Y[j]){
ans[j] = tree1.query(1, tin[T[j]]) + tree1.query(1, tin[S[j]]) - 2 * tree1.query(1, tin[L[j]]);
low[j] = i + 1;
}
else {
high[j] = i - 1;
}
}
if (i == m) continue;
int a = A[C[i + 1].second], val = C[i + 1].first;
tree1.update(tin[a], 1);
tree1.update(tout[a], -1);
tree2.update(tin[a], val);
tree2.update(tout[a], -val);
}
}
tree1.init();
for (int i = 1; i <= m; i++){
int a = A[C[i].second], val = C[i].first;
tree1.update(tin[a], 1);
tree1.update(tout[a], -1);
}
for (int i = 1; i <= q; i++) {
int gsum = tree1.query(1, tin[T[i]]) + tree1.query(1, tin[S[i]]) - 2 * tree1.query(1, tin[L[i]]);
if (X[i] + ans[i] >= gsum) printf("%d\n", max(0, X[i] + ans[i] - gsum));
else printf("-1\n");
}
return 0;
}
