#include <bits/stdc++.h>
using namespace std;
#define int long long
#define f first
#define s second
const int N = 2e5 + 69;
const int C = 1e9 + 69;
const int K = 18;
const int inf = 1e18;
int up[N][K];
int n, m, q, p[N], c[N], par[N], timer, tin[N], tout[N];
int root[N], lc[30 * N], rc[30 * N], node, vis[N];
int st[30 * N], cnt[30 * N];
vector<int> g[N];
vector<pair<int, int>> e;
map<pair<int, int>, vector<int>> edges;
void Modify(int v, int rt, int tl, int tr, int p) {
if (tl == tr) {
cnt[v] = cnt[rt] + 1;
st[v] = st[rt] + tl;
}
else {
int mid = (tl + tr) / 2;
if (p <= mid) {
lc[v] = ++node;
rc[v] = rc[rt];
Modify(lc[v], lc[rt], tl, mid, p);
}
else {
rc[v] = ++node;
lc[v] = lc[rt];
Modify(rc[v], rc[rt], mid + 1, tr, p);
}
st[v] = st[lc[v]] + st[rc[v]];
cnt[v] = cnt[lc[v]] + cnt[rc[v]];
}
}
int GetSum(int v, int v1, int v2, int tl, int tr, int l, int r) {
if (tl > r || tr < l)
return 0;
else if (tl >= l && tr <= r)
return st[v] + st[v1] - 2 * st[v2];
else {
int mid = (tl + tr) / 2;
return GetSum(lc[v], lc[v1], lc[v2], tl, mid, l, r) + GetSum(rc[v], rc[v1], rc[v2], mid + 1, tr, l, r);
}
}
int GetCnt(int v, int v1, int v2, int tl, int tr, int l, int r) {
if (tl > r || tr < l)
return 0;
else if (tl >= l && tr <= r)
return cnt[v] + cnt[v1] - 2 * cnt[v2];
else {
int mid = (tl + tr) / 2;
return GetCnt(lc[v], lc[v1], lc[v2], tl, mid, l, r) + GetCnt(rc[v], rc[v1], rc[v2], mid + 1, tr, l, r);
}
}
int Cnt(int v, int tl, int tr, int p) {
if (tl == tr)
return cnt[v];
else {
int mid = (tl + tr) / 2;
if (p <= mid)
return Cnt(lc[v], tl, mid, p);
else
return Cnt(rc[v], mid + 1, tr, p);
}
}
bool anc(int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
int lca(int a, int b) {
if (anc(a, b))
return a;
else if (anc(b, a))
return b;
for (int i = K - 1;i >= 0;i--) {
if (!anc(up[a][i], b) && up[a][i] > 0)
a = up[a][i];
}
return up[a][0];
}
void dfs(int v, int p) {
par[v] = p;
tin[v] = ++timer;
up[v][0] = p;
root[v] = root[p];
int x = v, y = p;
if (x > y)
swap(x, y);
if (edges.count({x, y})) {
for (auto u : edges[{x, y}]) {
int nr = ++node;
Modify(nr, root[v], 0, C, u);
root[v] = nr;
}
}
for (int i = 1;i < K;i++)
up[v][i] = up[up[v][i - 1]][i - 1];
for (auto u : g[v]) {
if (u == p)
continue;
dfs(u, v);
}
tout[v] = timer;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
cin >> n >> m >> q;
for (int i = 1;i <= n - 1;i++) {
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
e.push_back({a, b});
}
for (int i = 1;i <= m;i++) {
int p, x;
cin >> p >> x;
vis[p] = 1;
--p;
int a, b;
tie(a, b) = e[p];
if (a > b)
swap(a, b);
edges[{a, b}].push_back(x);
}
dfs(1, 0);
while (q--) {
int s, t, x, y;
cin >> s >> t >> x >> y;
int lc = lca(s, t);
int l = 0, r = C, ans = -1;
int uk = cnt[root[s]] + cnt[root[t]] - 2 * cnt[root[lc]];
auto Check = [&](int mid) {
int sum = GetSum(root[s], root[t], root[lc], 0, C, 0, mid);
int c = GetCnt(root[s], root[t], root[lc], 0, C, 0, mid);
return make_pair(sum, c);
};
while (l <= r) {
int mid = (l + r) / 2;
auto p = Check(mid);
if (p.f > y) {
int x = Cnt(root[s], 0, C, mid) + Cnt(root[t], 0, C, mid);
x -= 2 * Cnt(root[lc], 0, C, mid);
if (p.f - (x - 1) * mid <= y) {
int r = y - (p.f - x * mid);
p.s -= x;
p.s += r / mid;
p.f -= x * mid;
p.f += r / mid * mid;
}
}
if (p.f <= y) {
ans = p.s;
l = mid + 1;
}
else
r = mid - 1;
}
if (uk - ans <= x)
ans = x - (uk - ans);
else
ans = -1;
cout << ans << '\n';
}
}
return 0;
}
