#include <bits/stdc++.h>
using namespace std;
#define int long long
// #define double long double
#define endl '\n'
#define fastIO ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define setmin(x, y) x = min((x), (y))
#define setmax(x, y) x = max((x), (y))
#define sqr(x) ((x) * (x))
#define fi first
#define se second
#define aint(x) x.begin(), x.end()
// mt19937 hdp(chrono::high_resolution_clock::now().time_since_epoch().count());
// int rand(int l, int r){return l + ((hdp() % (r - l + 1)) + r - l + 1) % (r - l + 1);}
const int NM = 1e5 + 5;
const int LG = 18;
vector<int> g[NM];
vector<pair<int, int>> cost;
int n, m, q, lw[NM], ans[NM], tin[NM], up[NM][LG], timer, tout[NM], dep[NM];
pair<int, int> e[NM];
struct BIT
{
int dt[NM];
void reset()
{
memset(dt, 0, sizeof dt);
}
void upd(int i, int v)
{
for (; i <= n; i += i & -i)
dt[i] += v;
}
void upd(int l, int r, int v)
{
upd(l, v);
upd(r + 1, -v);
}
int get(int i)
{
int ans = 0;
for (; i; i -= i & -i)
ans += dt[i];
return ans;
}
}bit[4];
struct Query
{
int s, t, x, y, l, r, id, m, lca;
Query(int _s, int _t, int _x, int _y, int _l, int _r, int _id, int _lca) : s(_s), t(_t), x(_x), y(_y), l(_l), r(_r), id(_id), lca(_lca) {}
};
vector<Query> Q;
void dfs(int u)
{
for (int i = 1; up[u][i - 1]; i++)
up[u][i] = up[up[u][i - 1]][i - 1];
tin[u] = ++timer;
for (int v : g[u])
if (!tin[v])
{
dep[v] = dep[u] + 1;
up[v][0] = u;
dfs(v);
}
tout[u] = timer;
}
int lca(int u, int v)
{
while (dep[u] != dep[v])
{
if (dep[u] < dep[v])
swap(u, v);
int t = dep[u] - dep[v];
for (; t; t ^= t & -t)
u = up[u][__lg(t & -t)];
}
if (u == v)
return u;
for (int i = LG - 1; i >= 0; i--)
if (up[u][i] != up[v][i])
{
u = up[u][i];
v = up[v][i];
}
return up[u][0];
}
int myfloor(int x, int y)
{
return x / y;
}
void solve()
{
cin >> n >> m >> q;
for (int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
e[i] = {u, v};
}
dfs(1);
for (int i = 1; i < n; i++)
lw[i] = (tin[e[i].fi] > tin[e[i].se] ? e[i].fi : e[i].se);
while (m--)
{
int p, c;
cin >> p >> c;
cost.emplace_back(c, lw[p]);
}
sort(cost.begin(), cost.end());
for (int i = 1; i <= q; i++)
{
int s, t, x, y;
cin >> s >> t >> x >> y;
Q.emplace_back(tin[s], tin[t], x, y, 0, 1e9 + 1, i - 1, tin[lca(s, t)]);
}
while (1)
{
bit[0].reset();
bit[1].reset();
bool changed = 0;
vector<pair<int, int>> wait;
for (auto &query : Q)
if (query.l < query.r - 1)
{
changed = 1;
query.m = query.l + query.r >> 1;
wait.emplace_back(query.m, query.id);
}
sort(wait.begin(), wait.end());
int ptrl = 0, ptrr = 0;
for (auto query : wait)
{
while (ptrr < cost.size() && cost[ptrr].fi <= query.fi)
{
bit[0].upd(tin[cost[ptrr].se], tout[cost[ptrr].se], 1);
bit[1].upd(tin[cost[ptrr].se], tout[cost[ptrr].se], cost[ptrr].fi);
ptrr++;
}
while (ptrl < ptrr && cost[ptrl].fi < query.fi)
{
bit[0].upd(tin[cost[ptrl].se], tout[cost[ptrl].se], -1);
ptrl++;
}
Query &x = Q[query.se];
int path = bit[1].get(x.s) + bit[1].get(x.t) - 2 * bit[1].get(x.lca);
int cnt = bit[0].get(x.s) + bit[0].get(x.t) - 2 * bit[0].get(x.lca);
if (path - max(0ll, cnt - 1) * query.fi <= x.y)
x.l = x.m;
else
x.r = x.m;
}
if (!changed)
break;
}
// for (int i = 0; i < q; i++)
// cout << Q[i].l << ' ' << Q[i].r << ' ' << Q[i].m << endl;
vector<pair<int, int>> wait;
for (auto &query : Q)
wait.emplace_back(query.l, query.id);
sort(wait.begin(), wait.end());
int ptrl = 0, ptrr = 0;
bit[0].reset();
bit[1].reset();
for (auto t : cost)
bit[2].upd(tin[t.se], tout[t.se], 1);
for (auto query : wait)
{
while (ptrr < cost.size() && cost[ptrr].fi <= query.fi)
{
bit[0].upd(tin[cost[ptrr].se], tout[cost[ptrr].se], 1);
bit[1].upd(tin[cost[ptrr].se], tout[cost[ptrr].se], cost[ptrr].fi);
bit[3].upd(tin[cost[ptrr].se], tout[cost[ptrr].se], 1);
ptrr++;
}
while (ptrl < ptrr && cost[ptrl].fi < query.fi)
{
bit[0].upd(tin[cost[ptrl].se], tout[cost[ptrl].se], -1);
ptrl++;
}
Query &x = Q[query.se];
int path = bit[1].get(x.s) + bit[1].get(x.t) - 2 * bit[1].get(x.lca);
int cnt = bit[0].get(x.s) + bit[0].get(x.t) - 2 * bit[0].get(x.lca);
int cntt = min(cnt, myfloor(x.y - path + cnt * query.fi, query.fi));
// cout << x.y - path << endl;
int lmao = bit[2].get(x.s) + bit[2].get(x.t) - 2 * bit[2].get(x.lca);
int Lmao = bit[3].get(x.s) + bit[3].get(x.t) - 2 * bit[3].get(x.lca);
ans[x.id + 1] = x.x - (lmao - (Lmao - cnt + cntt));
}
for (int i = 1; i <= q; i++)
cout << (ans[i] < 0 ? -1 : ans[i]) << endl;
}
signed main()
{
fastIO
if (fopen("in.txt", "r"))
{
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
}
int tc = 1; // cin >> tc;
while (tc--)
solve();
}
