#include<bits/stdc++.h>
//#include <grader.h>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define ll long long
#define ld long double
#define st first
#define nd second
#define pb push_back
#define INF INT_MAX
using namespace std;
const int N = 1e5 + 10;
const int L = log2(N)+1;
struct node{
ll val, cnt;
ll lc, rc;
}seg[20*N];
vector<pll> adj[N];
vector<ll> cost[N];
map<ll, ll> mp, rv;
ll up[N][L], lvl[N], cnt, root[N];
void update(ll &cur, ll l, ll r, ll x, ll val) {
cnt++;
seg[cnt] = seg[cur];
cur = cnt;
if (l==r) {
seg[cur].val = val;
seg[cur].cnt = 1;
return;
}
int mid = (l+r)/2;
if (x <= mid) update(seg[cur].lc, l, mid, x, val);
else update(seg[cur].rc, mid+1, r, x, val);
seg[cur].val = seg[seg[cur].rc].val + seg[seg[cur].lc].val;
seg[cur].cnt = seg[seg[cur].rc].cnt + seg[seg[cur].lc].cnt;
}
ll query(ll curu, ll curv, ll curc, ll l, ll r, ll x, ll ans) {
if (l==r) {
if (x >= seg[curu].val + seg[curv].val - 2*seg[curc].val)
return ans + seg[curu].cnt + seg[curv].cnt - 2*seg[curc].cnt;
else
return ans;
}
ll mid = (l+r)/2;
ll nxt = seg[seg[curu].lc].val + seg[seg[curv].lc].val - 2*seg[seg[curc].lc].val;
ll lft = seg[seg[curu].lc].cnt + seg[seg[curv].lc].cnt - 2*seg[seg[curc].lc].cnt;
if (nxt > x) return query(seg[curu].lc, seg[curv].lc, seg[curc].lc, l, mid, x, ans);
else return query(seg[curu].rc, seg[curv].rc, seg[curc].rc, mid+1, r, x-nxt, ans+lft);
}
void dfs(ll a, ll prt) {
up[a][0] = prt; lvl[a] = lvl[prt]+1;
for (int i = 1; i < L; ++i) up[a][i] = up[up[a][i-1]][i-1];
for (auto [b, idx] : adj[a]) if (b != prt) dfs(b, a);
}
ll lca(ll a, ll b) {
if (lvl[a] < lvl[b]) swap(a, b);
ll j = lvl[a]-lvl[b];
for (int i = 0; i < L; ++i) if (j&(1<<i)) a = up[a][i];
if (a==b) return a;
for (int i = L-1; i >= 0; --i) if (up[a][i] != up[b][i]) a = up[a][i], b = up[b][i];
return up[a][0];
}
void build(int a, int prt) {
for (auto [b, i] : adj[a]) {
if (b == prt) continue;
root[b] = root[a];
for (auto c : cost[i]) update(root[b], 1, 100000, mp[c], rv[c]);
build(b, a);
}
}
void solve() {
int n, m, q; cin >> n >> m >> q;
for (int i = 1; i < n; ++i) {
ll a, b; cin >> a >> b;
adj[a].pb({b, i});
adj[b].pb({a, i});
}
vector<pll> v; ll tmp = 0;
for (int i = 1; i <= m; ++i) {
ll p, c; cin >> p >> c;
cost[p].pb(i); v.pb({c, i});
}
sort(v.begin(), v.end());
for (auto i : v) mp[i.nd] = ++tmp, rv[i.nd] = i.st;
dfs(1, 0);
build(1, 0);
while (q--) {
ll s, t, x, y; cin >> s >> t >> x >> y;
ll c = lca(s, t);
ll rmn = query(root[s], root[t], root[c], 1, 100000, 1e18, 0) - query(root[s], root[t], root[c], 1, 100000, y, 0);
if (rmn > x) cout << -1 << '\n';
else cout << x-rmn << '\n';
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(NULL);
int t = 1;
// cin >> t;
while (t--) {
solve();
}
return 0;
}
