#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
//#define int long long
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
struct Node {
ll sum, cnt;
Node *l, *r;
Node(ll a, ll b) : sum(a), cnt(b), l(nullptr), r(nullptr) {}
Node(Node *l, Node *r) : sum(0), cnt(0), l(l), r(r) {
if(l) sum += l->sum;
if(l) cnt += l->cnt;
if(r) sum += r->sum;
if(r) cnt += r->cnt;
}
};
Node* build(int tl, int tr) {
if(tl == tr) return new Node((ll)0, (ll)0);
int tm = (tl + tr) / 2;
return new Node(build(tl, tm), build(tm+1, tr));
}
Node* update(Node *u, int tl, int tr, int p, ll v) {
if(tl == tr) return new Node(u->sum + v, u->cnt + (v > 0 ? 1 : -1));
int tm = (tl + tr) / 2;
if(p <= tm) return new Node(update(u->l, tl, tm, p, v), u->r);
return new Node(u->l, update(u->r, tm+1, tr, p, v));
}
pll merge(pll a, pll b) {
return { a.first + b.first, a.second + b.second };
}
pll query(Node *u, int tl, int tr, int l, int r) {
if(tl > r || l > tr) return { 0, 0 };
if(l <= tl && tr <= r) return { u->sum, u->cnt };
int tm = (tl + tr) / 2;
return merge(query(u->l, tl, tm, l, r), query(u->r, tm+1, tr, l, r));
}
vector<int> graph[maxn], vals[maxn], in(maxn), out(maxn), d(maxn), euler;
int timer = 0, up[maxn][20], cnt[maxn][20];
void dfs_init(int u, int p) {
in[u] = timer++; euler.push_back(u);
for(int i=1; i<20; i++) up[u][i] = up[up[u][i-1]][i-1];
for(int &v : graph[u]) {
if(v == p) continue;
d[v] = d[u] + 1;
up[v][0] = u;
dfs_init(v, u);
}
out[u] = timer++;
euler.push_back(u);
}
void dfs2(int u, int p) {
for(int i=1; i<20; i++) cnt[u][i] = cnt[u][i-1] + cnt[up[u][i-1]][i-1];
for(int &v : graph[u]) {
if(v == p) continue;
dfs2(v, u);
}
}
int get_lca(int a, int b) {
if(d[a] < d[b]) swap(a, b);
int D = d[a] - d[b];
for(int j=19; j>=0; j--)
if(D & (1 << j)) a = up[a][j];
if(a == b) return a;
for(int j=19; j>=0; j--)
if(up[a][j] != up[b][j]) a = up[a][j], b = up[b][j];
return up[a][0];
}
int get_cnt(int a, int b) {
if(d[a] < d[b]) swap(a, b);
int D = d[a] - d[b], ans = 0;
for(int j=19; j>=0; j--)
if(D & (1 << j)) ans += cnt[a][j], a = up[a][j];
if(a == b) return ans;
for(int j=19; j>=0; j--) {
if(up[a][j] != up[b][j]) {
ans += cnt[a][j] + cnt[b][j];
a = up[a][j]; b = up[b][j];
}
}
return ans + cnt[a][0] + cnt[b][0];
}
signed main() {
ios_base::sync_with_stdio(false);
cout.tie(0); cin.tie(0);
int n, m, q;
cin >> n >> m >> q;
vector<array<int, 2> > edges;
const int B = sqrt(2 * n);
for(int i=0; i<n-1; i++) {
int a, b; cin >> a >> b;
graph[a].push_back(b);
graph[b].push_back(a);
edges.push_back({ a, b });
}
dfs_init(1, 1);
vector<pll> vec;
for(int i=0; i<m; i++) {
int id, x; cin >> id >> x;
if(d[edges[id-1][0]] > d[edges[id-1][1]]) swap(edges[id-1][0], edges[id-1][1]);
vec.push_back({ x, edges[id-1][1] });
cnt[edges[id-1][1]][0]++;
}
dfs2(1, 1);
sort(vec.begin(), vec.end());
vector<Node*> roots; roots.push_back(build(0, 2*n-1));
for(auto &[val, u] : vec) {
roots.push_back(update(roots.back(), 0, 2*n-1, in[u], val));
roots.push_back(update(roots.back(), 0, 2*n-1, out[u], -val));
}
auto Q = [&](int t, int a, int b) {
pll x = query(roots[t], 0, 2*n-1, 0, in[a]);
pll y = query(roots[t], 0, 2*n-1, 0, in[b]);
pll z = query(roots[t], 0, 2*n-1, 0, in[get_lca(a, b)]);
return pll{ x.first + y.first - 2 * z.first, x.second + y.second - 2 * z.second };
};
while(q--) {
ll a, b, G, S;
cin >> a >> b >> G >> S;
if(a == b) {
cout << G << '\n';
continue;
}
ll total = get_cnt(a, b);
int l=0, r=m, can=0;
while(l <= r) {
int mid = (l + r) / 2;
auto res = Q(2*mid, a, b);
if(res.first <= S) can = res.second, l = mid + 1;
else r = mid - 1;
}
cout << max(-1ll, G - total + can) << '\n';
}
return 0;
}
