#include <bits/stdc++.h>
#define fi first
#define se second
const int N = 100100;
using namespace std;
int n, m, q;
int dip[N];
int f[N][20];
int tin[N];
int tout[N];
int tim;
long long F[N], F2[N];
int A[N], B[N];
vector<int> v[N];
pair<int, int> cp[N];
int par[N];
int s[N], t[N], x[N], y[N];
int tl[N], tr[N];
vector<int> qu[N], nqu[N];
int C[N], D[N];
void dfs(int x, int p)
{
tin[x] = ++tim;
f[x][0] = p;
for (int i = 1; i < 20; i++) {
f[x][i] = f[f[x][i - 1]][i - 1];
}
for (int i: v[x]) {
int y = A[i] ^ B[i] ^ x;
if (y == p) {
continue;
}
dip[y] = dip[x] + 1;
dfs(y, x);
}
tout[x] = tim;
}
bool isp(int x, int y)
{
return tin[x] <= tin[y] && tout[x] >= tout[y];
}
int lca(int x, int y)
{
if (isp(x, y)) {
return x;
} else if(isp(y, x)){
return y;
}
for (int i = 19; i >= 0; i--) {
if (!isp(f[x][i], y)) {
x = f[x][i];
}
}
return f[x][0];
}
void upd(int x, int y)
{
while (x < N) {
F[x] += y;
x += x & -x;
}
}
long long get(int x)
{
long long res = 0;
while (x > 0) {
res += F[x];
x -= x & -x;
}
return res;
}
void upd2(int x, int y)
{
while (x < N) {
F2[x] += y;
x += x & -x;
}
}
long long get2(int x)
{
long long res = 0;
while (x > 0) {
res += F2[x];
x -= x & -x;
}
return res;
}
int main()
{
#ifdef zxc
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin >> n >> m >> q;
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y;
v[x].push_back(i);
v[y].push_back(i);
A[i] = x;
B[i] = y;
}
for (int i = 1; i <= m; i++) {
cin >> cp[i].se >> cp[i].fi;
}
sort(cp + 1, cp + m + 1);
for (int i = 1; i <= q; i++) {
cin >> s[i] >> t[i] >> x[i] >> y[i];
tl[i] = 0;
tr[i] = m;
}
dfs(1, 1);
for (int i = 1; i < n; i++) {
if (dip[A[i]] > dip[B[i]]) {
swap(A[i], B[i]);
}
}
for (int i = 1; i <= q; i++) {
par[i] = lca(s[i], t[i]);
}
for (int it = 1; it <= 22; it++) {
for (int i = 1; i <= q; i++) {
int tm = (tl[i] + tr[i]) / 2 + (tl[i] < tr[i]);
//cout << tl[i] << " " << tr[i] << " " << tm << endl;
if (tl[i] <= tr[i]) {
qu[tm].push_back(i);
}
}
for (int i = 0; i <= m; i++) {
if (i > 0) {
int j = cp[i].se;
upd(tin[B[j]], cp[i].fi);
upd(tout[B[j]] + 1, -cp[i].fi);
upd2(tin[B[j]], 1);
upd2(tout[B[j]] + 1, -1);
}
for (int j: qu[i]) {
long long tot = get(tin[s[j]]) + get(tin[t[j]]) - 2 * get(tin[par[j]]);
long long col = get2(tin[s[j]]) + get2(tin[t[j]]) - 2 * get2(tin[par[j]]);
C[j] = tot;
D[j] = col;
if (tot <= y[j]) {
tl[j] = i;
} else {
tr[j] = i - 1;
}
}
}
for (int i = 0; i < N; i++) {
F[i] = F2[i] = 0;
qu[i].clear();
}
}
for (int i = 1; i <= m; i++) {
int j = cp[i].se;
upd2(tin[B[j]], 1);
upd2(tout[B[j]] + 1, -1);
}
for (int i = 1; i <= q; i++) {
int golds = get2(tin[s[i]]) + get2(tin[t[i]]) - 2 * get2(tin[par[i]]);
//cout << golds << " " << D[i] << " " << tl[i] << " " << tr[i] << endl;
golds = x[i] - (golds - D[i]);
cout << max(golds, -1) << "\n";
}
}
