#include <bits/stdc++.h>
using namespace std;
void setup()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
struct NODE
{
int l = 0, r = 0, num = 0;
long long sum = 0;
};
struct PERSISTENT_SEGMENT_TREE
{
int sz = 1; // use tree[0] as a virtual node store nothing
NODE tree[2000000];
inline void Update(int &ind, int l, int r, int x, int v)
{
if (r < x || x < l)
{
return;
}
tree[sz] = tree[ind];
ind = sz++;
tree[ind].num++;
tree[ind].sum += v;
if (l < r)
{
int m = (l + r) >> 1;
Update(tree[ind].l, l, m, x, v);
Update(tree[ind].r, m + 1, r, x, v);
}
}
inline int Num(int x, int y, int z)
{
return tree[x].num + tree[y].num - 2 * tree[z].num;
}
inline long long Sum(int x, int y, int z)
{
return tree[x].sum + tree[y].sum - 2 * tree[z].sum;
}
inline int Get(int l, int r, int x, int y, int z, long long rem)
{
if (Num(x, y, z) <= 1)
{
return (Sum(x, y, z) <= rem) * Num(x, y, z);
}
int m = (l + r) >> 1;
if (rem <= Sum(tree[x].l, tree[y].l, tree[z].l))
{
return Get(l, m, tree[x].l, tree[y].l, tree[z].l, rem);
}
rem -= Sum(tree[x].l, tree[y].l, tree[z].l);
return Num(tree[x].l, tree[y].l, tree[z].l) +
Get(m + 1, r, tree[x].r, tree[y].r, tree[z].r, rem);
}
} st;
int n, m, q, a, b, c[100000], d[100000], gold, rem;
int sp[20][100000], depth[100000], root[100000];
long long silver;
vector<pair<int, int>> g[100000], p;
vector<int> v[100000];
inline void DFS(int node, int par, int last = -1)
{
sp[0][node] = par;
for (int i = 1; i < 20; ++i)
{
sp[i][node] = sp[i - 1][sp[i - 1][node]];
}
root[node] = root[par];
if (last != -1)
{
for (auto &i : v[last])
{
st.Update(root[node], 1, m, d[i], c[i]);
}
}
// each node store a root of a segment tree that have the data of the road from 1 to node
for (auto &i : g[node])
{
if (i.first != par)
{
depth[i.first] = depth[node] + 1;
DFS(i.first, node, i.second);
}
}
}
inline int LCA(int ina, int inb)
{
if (depth[ina] != depth[inb])
{
if (depth[ina] < depth[inb])
{
swap(ina, inb);
}
for (int i = 19; i >= 0; --i)
{
if (depth[sp[i][ina]] >= depth[inb])
{
ina = sp[i][ina];
}
}
}
if (ina == inb)
{
return ina;
}
for (int i = 19; i >= 0; --i)
{
if (sp[i][ina] != sp[i][inb])
{
ina = sp[i][ina];
inb = sp[i][inb];
}
}
return sp[0][ina];
}
int main()
{
setup();
cin >> n >> m >> q;
for (int i = 0; i < n - 1; ++i)
{
cin >> a >> b;
g[a - 1].push_back({b - 1, i});
g[b - 1].push_back({a - 1, i});
}
for (int i = 0; i < m; ++i)
{
cin >> a >> c[i];
p.push_back({c[i], i});
v[a - 1].push_back(i);
}
sort(p.begin(), p.end());
for (int i = 0; i < p.size(); ++i)
{
d[p[i].second] = i + 1;
}
DFS(0, 0);
while (q--)
{
cin >> a >> b >> gold >> silver;
a--;
b--;
rem = st.Num(root[a], root[b], root[LCA(a, b)]) -
st.Get(1, m, root[a], root[b], root[LCA(a, b)], silver);
cout << max(-1, gold - rem) << "\n";
}
return 0;
}
