#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 1e5 + 10;
int n, m, q, it;
int road[N << 1], st[N], ed[N], h[N], par[18][N];
vector<int> adj[N];
vector<ll> vt, gin[N];
pair<int, int> e[N];
void init() {
cin>>n>>m>>q;
for(int i = 1; i <= n - 1; ++i) {
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
e[i] = {u, v};
}
}
void dfs(int u) {
road[++it] = u;
st[u] = it;
for(auto v : adj[u]) if(v != par[0][u]) {
h[v] = h[u] + 1;
par[0][v] = u;
for(int i = 1; i <= log2(n); ++i) par[i][v] = par[i - 1][par[i - 1][v]];
dfs(v);
}
road[++it] = u;
ed[u] = it;
}
int lca(int x, int y) {
if(h[x] < h[y]) swap(x, y);
int delta = h[x] - h[y];
for(int i = 0; i <= log2(n); ++i) if((delta >> i) & 1) {
x = par[i][x];
}
if(x == y) return x;
for(int i = log2(n); i >= 0; --i) if(par[i][x] != par[i][y]) {
x = par[i][x];
y = par[i][y];
}
return par[0][x];
}
int child(int p, int x) {
int delta = h[x] - h[p] - 1;
if(delta == -1) return st[p];
for(int i = 0; i <= log2(n); ++i) if((delta >> i) & 1) {
x = par[i][x];
}
return st[x] - 1;
}
struct Tree {
ll cnt, sum;
Tree* lf;
Tree* rt;
Tree() : sum(), cnt(), lf(), rt() { }
};
ll sum(Tree* id) {
return id ? id -> sum : 0;
}
ll cnt(Tree* id) {
return id ? id -> cnt : 0;
}
void up(Tree* id, int f, int l, int i, ll val1, ll val2) {
if(f == l) {
id -> sum += val1;
id -> cnt += val2;
return;
}
int mid = f + l >> 1;
if(i <= mid) {
id -> lf = id -> lf ? new Tree(*id -> lf) : new Tree();
up(id -> lf, f, mid, i, val1, val2);
}
else {
id -> rt = id -> rt ? new Tree(*id -> rt) : new Tree();
up(id -> rt, mid + 1, l, i, val1, val2);
}
id -> sum = sum(id -> lf) + sum(id -> rt);
id -> cnt = cnt(id -> lf) + cnt(id -> rt);
}
ll get(Tree* fu, Tree* lu, Tree* fv, Tree* lv, int f, int l, ll val) {
if(f == l) {
ll dd = val / vt[f - 1];
ll gold = cnt(lu) - cnt(fu) + cnt(lv) - cnt(fv);
return max(0ll, gold - dd);
}
int mid = f + l >> 1;
ll silver = sum(lu -> lf) - sum(fu -> lf) + sum(lv -> lf) - sum(fv -> lf);
if(silver >= val) {
if(!fu -> lf) fu -> lf = new Tree(); if(!lu -> lf) lu -> lf = new Tree();
if(!fv -> lf) fv -> lf = new Tree(); if(!lv -> lf) lv -> lf = new Tree();
ll gold = cnt(lu -> rt) - cnt(fu -> rt) + cnt(lv -> rt) - cnt(fv -> rt);
return get(fu -> lf, lu -> lf, fv -> lf, lv -> lf, f, mid, val) + gold;
}
else {
if(!fu -> rt) fu -> rt = new Tree(); if(!lu -> rt) lu -> rt = new Tree();
if(!fv -> rt) fv -> rt = new Tree(); if(!lv -> rt) lv -> rt = new Tree();
return get(fu -> rt, lu -> rt, fv -> rt, lv -> rt, mid + 1, l, val - silver);
}
}
int32_t main () {
cin.tie(0)->sync_with_stdio(0);
if(fopen("Task.inp","r")) {
freopen("Task.inp","r",stdin);
freopen("WA.out","w",stdout);
}
init();
dfs(1);
while(m--) {
int r; ll c; cin>>r>>c;
int u, v; tie(u, v) = e[r];
if(h[u] < h[v]) swap(u, v);
gin[u].push_back(c);
vt.push_back(c);
}
sort(vt.begin(), vt.end());
vt.resize(unique(vt.begin(), vt.end()) - vt.begin());
int mx = vt.size();
vector<Tree*> tr;
tr.resize(it + 1);
tr[0] = new Tree();
for(int i = 1; i <= it; ++i) {
int u = road[i];
tr[i] = new Tree(*tr[i - 1]);
if(i == st[u]) for(auto c : gin[u]) {
int pos = upper_bound(vt.begin(), vt.end(), c) - vt.begin();
up(tr[i], 1, mx, pos, c, 1);
}
if(i == ed[u]) for(auto c : gin[u]) {
int pos = upper_bound(vt.begin(), vt.end(), c) - vt.begin();
up(tr[i], 1, mx, pos, -c, -1);
}
}
while(q--) {
int s, t, x; ll y; cin >> s >> t >> x >> y;
if(st[s] > st[t]) swap(s, t);
int p = lca(s, t);
int u = child(p, s);
int v = child(p, t);
ll ans = get(tr[u], tr[st[s]], tr[v], tr[st[t]], 1, mx, y);
if(ans > x) cout << "-1\n";
else cout << x - ans << "\n";
}
}
