#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<ll, ll> pii;
pii operator+(const pii &a, const pii &b) { return {a.first + b.first, a.second + b.second}; }
typedef vector<pii> vpii;
typedef vector<vpii> vvpii;
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
int N, M, Q;
vi A, B;
vector<vector<ll>> C;
vpii D; // what to delete
vvpii adj;
vi in, out;
vvi vorg;
vi ein, eout; // edges to corresponding in and outs
vi R; // binary search those roots
struct segtree
{
int size;
vpii arr;
vi L, R;
vi roots;
int newNode()
{
arr.push_back({0, 0}), L.push_back(-1), R.push_back(-1);
return sz(arr) - 1;
}
void init(int _size)
{
size = 1;
while (size < _size)
size *= 2;
arr.assign(2 * size, {0, 0});
L.assign(2 * size, -1), R.assign(2 * size, -1);
roots.push_back(1);
for (int i = 1; i < size; ++i)
L[i] = 2 * i, R[i] = 2 * i + 1;
}
int add(int i, pii v)
{
int idx = newNode();
add(i, v, idx, roots.back(), 0, size);
roots.push_back(idx);
return idx;
}
void add(int i, pii v, int newX, int oldX, int lx, int rx)
{
L[newX] = L[oldX], R[newX] = R[oldX], arr[newX] = arr[oldX];
if (rx - lx == 1)
{
arr[newX] = arr[oldX] + v;
return;
}
int m = (lx + rx) / 2;
int idx = newNode();
if (i < m)
{
L[newX] = idx;
add(i, v, L[newX], L[oldX], lx, m);
}
else
{
R[newX] = idx;
add(i, v, R[newX], R[oldX], m, rx);
}
arr[newX] = arr[L[newX]] + arr[R[newX]];
}
pii summe(int l, int r, int x)
{
return summe(l, r, x, 0, size);
}
pii summe(int l, int r, int x, int lx, int rx)
{
if (l <= lx && rx <= r)
return arr[x];
if (r <= lx || rx <= l)
return {0, 0};
int m = (lx + rx) / 2;
pii a = summe(l, r, L[x], lx, m);
pii b = summe(l, r, R[x], m, rx);
return a + b;
// return {a.first + b.first, a.second + b.second};
}
};
segtree seg;
void dfs(int v, int p, int e, int &idx)
{
vorg[v][0] = p;
for (int i = 1; i < sz(vorg[v]); ++i)
vorg[v][i] = vorg[vorg[v][i - 1]][i - 1];
in[v] = idx;
if (e != -1)
ein[e] = idx;
++idx;
for (pii ed : adj[v])
{
if (ed.first == p)
continue;
dfs(ed.first, v, ed.second, idx);
}
out[v] = idx;
if (e != -1)
eout[e] = idx;
++idx;
}
bool isVorg(int a, int b)
{
return in[a] <= in[b] && out[b] <= out[a];
}
int lca(int a, int b)
{
if (isVorg(a, b))
return a;
if (isVorg(b, a))
return b;
int tmp;
for (int i = sz(vorg[0]) - 1; i >= 0; --i)
{
tmp = vorg[a][i];
if (!isVorg(tmp, b))
a = tmp;
}
return vorg[a][0];
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
cin >> N >> M >> Q;
adj.resize(N);
A.resize(N - 1), B.resize(N - 1);
for (int i = 0; i < N - 1; ++i)
{
cin >> A[i] >> B[i];
--A[i], --B[i];
adj[A[i]].push_back({B[i], i});
adj[B[i]].push_back({A[i], i});
}
in.resize(N), out.resize(N);
ein.resize(N - 1), eout.resize(N - 1);
vorg.assign(N, vi(ceil(log2(N)) + 1));
int idx = 0;
dfs(0, 0, -1, idx);
C.resize(N - 1);
for (int i = 0, p, c; i < M; ++i)
{
cin >> p >> c;
--p;
C[p].push_back(c);
D.push_back({c, p});
}
seg.init(2 * N);
for (int i = 0; i < N - 1; ++i)
{
if (!C[i].empty())
{
seg.add(ein[i], {0, accumulate(all(C[i]), 0LL)});
seg.add(eout[i], {0, -accumulate(all(C[i]), 0LL)});
}
}
sort(all(D));
reverse(all(D));
R.push_back(seg.roots.back());
for (pii d : D)
{
seg.add(ein[d.second], {1, -d.first});
R.push_back(seg.add(eout[d.second], {-1, d.first}));
}
while (Q--)
{
int s, t;
ll x, y;
cin >> s >> t >> x >> y;
--s, --t;
int lc = lca(s, t);
int l = 0, r = sz(R), m;
while (l < r)
{
m = (l + r) / 2;
pii ans = seg.summe(in[lc] + 1, in[s] + 1, R[m]) + seg.summe(in[lc] + 1, in[t] + 1, R[m]);
if (ans.second > y)
l = m + 1;
else
r = m;
}
if (l == sz(R))
cout << "-1\n";
else
{
pii ans = seg.summe(in[lc] + 1, in[s] + 1, R[l]) + seg.summe(in[lc] + 1, in[t] + 1, R[l]);
if (ans.second <= y && ans.first <= x)
cout << x - ans.first << "\n";
else
cout << "-1\n";
}
}
return 0;
}
