#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
const int MAXN = 1e5+5;
const int MAXB = 17;
int n, m, q;
vector<pii> edges[MAXN];
vector<int> at_edge[MAXN];
int cost[MAXN];
int pos[MAXN];
int lca[MAXN][MAXB];
int depth[MAXN];
class stree {
public:
int lp, rp;
stree *l = nullptr;
stree *r = nullptr;
ll sum = 0;
int num = 0;
stree(int lv, int rv) {
lp = lv;
rp = rv;
if (lp < rp) {
int mid = (lp+rp)/2;
l = new stree(lp, mid);
r = new stree(mid+1, rp);
}
}
stree(stree *prev, int v) {
assert(!prev->l);
sum = prev->sum+v;
num = prev->num+1;
lp = prev->lp;
rp = prev->rp;
}
stree(stree *l, stree *r) : l(l), r(r) {
sum = l->sum+r->sum;
num = l->num+r->num;
lp = l->lp;
rp = r->rp;
}
stree *upd(int p, int v) {
if (lp > p || rp < p) return this;
if (lp == rp) return new stree(this, v);
return new stree(l->upd(p, v), r->upd(p, v));
}
};
stree *trees[MAXN];
void dfs(int cur, int p = -1) {
for (pii e: edges[cur]) {
int nxt = e.first;
if (nxt == p) continue;
trees[nxt] = trees[cur];
for (int v: at_edge[e.second]) {
trees[nxt] = trees[nxt]->upd(pos[v], cost[v]);
}
lca[nxt][0] = cur;
depth[nxt] = 1+depth[cur];
dfs(nxt, cur);
}
}
int get_lca(int s, int t) {
if (depth[s] < depth[t]) swap(s, t);
for (int i = MAXB-1; i >= 0 && depth[s] > depth[t]; i--) {
if ((1<<i) <= depth[s]-depth[t]) s = lca[s][i];
}
if (s == t) return s;
for (int i = MAXB-1; i >= 0; i--) {
if (lca[s][i] != lca[t][i]) {
s = lca[s][i];
t = lca[t][i];
}
}
assert(s != t);
assert(lca[s][0] == lca[t][0]);
return lca[s][0];
}
int walk(stree *a, stree *b, stree *c, ll &amt) { // return max num you can buy with this amt
if (amt == 0) return 0;
if (a->sum+b->sum-2*c->sum <= amt) {
amt -= (a->sum+b->sum-2*c->sum);
return (a->num+b->num-2*c->num);
}
else if (!a->l) {
amt = 0;
return 0;
}
int v = walk(a->l, b->l, c->l, amt);
return v + walk(a->r, b->r, c->r, amt);
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> n >> m >> q;
for (int i = 0; i < n-1; i++) {
int x, y; cin >> x >> y; x--; y--;
edges[x].push_back(pii(y, i));
edges[y].push_back(pii(x, i));
}
vector<pii> sortable;
for (int i = 0; i < m; i++) {
int p, w; cin >> p >> w;
p--;
at_edge[p].push_back(i);
cost[i] = w;
sortable.push_back(pii(w, i));
}
sort(sortable.begin(), sortable.end());
for (int i = 0; i < m; i++) pos[sortable[i].second] = i;
trees[0] = new stree(0, m-1);
dfs(0);
for (int j = 1; j < MAXB; j++) {
for (int i = 0; i < n; i++) lca[i][j] = lca[lca[i][j-1]][j-1];
}
for (int i = 0; i < q; i++) {
int s, t, x; ll y; cin >> s >> t >> x >> y;
s--; t--;
int l = get_lca(s, t);
int rem = trees[s]->num+trees[t]->num-2*trees[l]->num-walk(trees[s], trees[t], trees[l], y);
if (rem <= x) cout << x-rem << '\n';
else cout << "-1\n";
}
}
