#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 2e5 + 5;
const int mxs = 1e14;
int32_t n, m, q;
vector<int> adj[MAXN];
int st[MAXN], en[MAXN], cur = 0;
bool is[MAXN];
int cost[MAXN];
pair<int,int> anc[19][2*MAXN];
int dep[MAXN];
vector<int> euler;
int dfn[2*MAXN];
void dfs(int node, int prv) {
st[node] = ++cur;
dfn[cur] = node;
euler.push_back(node);
dep[node] = (prv == -1 ? 0 : dep[prv] + 1);
for(int x: adj[node]) {
if(x != prv) {
dfs(x, node);
euler.push_back(node);
}
}
en[node] = ++cur;
dfn[cur] = node;
}
int ans[MAXN];
int block;
int32_t s[MAXN], t[MAXN], x[MAXN];
int y[MAXN], p[MAXN]; //lca
int mi[MAXN], ma[MAXN], ord[MAXN];
int l[MAXN], r[MAXN];
int lca(int u, int v) {
int m1 = min(mi[u], mi[v]), m2 = max(ma[u], ma[v]);
int k = 32 - __builtin_clz(m2-m1+1) - 1;
return min(anc[k][m1], anc[k][m2 - (1<<k) + 1]).second;
}
bool cmp(int qa, int qb) {
if(l[qa] / block != l[qb] / block) return l[qa] / block < l[qb] / block;
return r[qa] < r[qb];
}
pair<int,int> chkpt[MAXN];
int freq[MAXN];
int pos[MAXN];
int val[MAXN];
int sumblock[MAXN];
int cnt[MAXN];
inline void ins(int x) {
int pp = pos[x];
val[pp] = cost[x];
cnt[pp / block]++;
sumblock[pp / block] += cost[x];
}
inline void del(int x) {
int pp = pos[x];
val[pp] = 0;
cnt[pp / block]--;
sumblock[pp / block] -= cost[x];
}
inline void add(int x) {
x = dfn[x];
if(!is[x]) return;
freq[x]++;
if(freq[x] == 2) del(x);
else ins(x);
}
inline void sub(int x) {
x = dfn[x];
if(!is[x]) return;
freq[x]--;
if(freq[x] == 0) del(x);
else ins(x);
}
pair<int,int> sto[MAXN];
vector<int> stuff[MAXN];
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
long long rnd(long long x, long long y) {
long long u = uniform_int_distribution<long long>(x, y)(rng);
return u;
}
int32_t main() {
ios::sync_with_stdio(0);
cin.tie(0);
scanf("%d %d %d", &n, &m, &q);
for(int i=0; i+1<n; i++) {
int32_t u, v;
scanf("%d %d", &u, &v);
sto[i] = {u, v};
}
int rt = rnd(1, n);
for(int i=0; i<m; i++) {
int32_t p, c;
scanf("%d %d", &p, &c);
n++;
p--;
stuff[p].push_back(n);
is[n] = 1;
cost[n] = c;
chkpt[i] = {c, n};
}
for(int i=0; i+1<n-m; i++) {
int u = sto[i].first;
int v = sto[i].second;
if(stuff[i].empty()) {
adj[u].push_back(v);
adj[v].push_back(u);
}
else {
adj[u].push_back(stuff[i][0]);
adj[stuff[i][0]].push_back(u);
for(int j=0; j+1<stuff[i].size(); j++) {
adj[stuff[i][j]].push_back(stuff[i][j+1]);
adj[stuff[i][j+1]].push_back(stuff[i][j]);
}
int fin = stuff[i].size() - 1;
adj[stuff[i][fin]].push_back(v);
adj[v].push_back(stuff[i][fin]);
}
}
block = ceil(sqrt(n)) * 2;
sort(chkpt, chkpt + m);
for(int i=0; i<m; i++) pos[chkpt[i].second] = i;
dfs(rt, -1);
for(int i=0; i<euler.size(); i++) anc[0][i] = {dep[euler[i]], euler[i]};
for(int i=0; i<euler.size(); i++) ma[euler[i]] = i;
for(int i=euler.size()-1; i>=0; i--) mi[euler[i]] = i;
for(int i=1; i<19; i++) {
for(int j=0; j+(1<<i)-1<euler.size(); j++) {
anc[i][j] = min(anc[i-1][j], anc[i-1][j+(1<<(i-1))]);
}
}
for(int i=1; i<=q; i++) {
scanf("%d %d %d %lld", &s[i], &t[i], &x[i], &y[i]);
if(st[s[i]] > st[t[i]]) swap(s[i], t[i]);
p[i] = lca(s[i], t[i]);
if(s[i] == p[i]) l[i] = st[s[i]], r[i] = st[t[i]];
else l[i] = en[s[i]], r[i] = st[t[i]];
}
for(int i=1; i<=q; i++) ord[i] = i;
sort(ord+1, ord+q+1, cmp);
block = ceil(sqrt(m));
int lprev = 0, rprev = 0;
for(int i=1; i<=q; i++) {
int idx = ord[i];
int lnew = l[idx], rnew = r[idx];
while(rprev < rnew) {
rprev++; add(rprev);
}
while(lprev > lnew) {
lprev--; add(lprev);
}
while(rprev > rnew) {
sub(rprev); rprev--;
}
while(lprev < lnew) {
sub(lprev); lprev++;
}
int run = 0; // number of checkpoints payable using silver
int gold = x[idx], silver = y[idx];
if(silver >= mxs) {
ans[idx] = gold;
continue;
}
int tcc = 0;
bool pk = 0;
for(int j=0; j<block; j++) {
tcc += cnt[j];
if(pk)continue;
if(sumblock[j] <= silver) {
silver -= sumblock[j];
run += cnt[j];
}
else {
int mlm = min((int) m, (j+1) * block);
for(int k=j*block; k<mlm; k++) {
if(val[k] <= silver && val[k] > 0) {
silver -= val[k];
run++;
}
}
pk = 1;
}
}
gold -= (tcc - run);
gold = max(gold, -1ll);
ans[idx] = gold;
}
for(int i=1; i<=q; i++) cout << ans[i] << "\n";
}
/*
4 6 1
1 2
2 3
1 4
2 1
4 1
3 5
3 2
4 2
3 2
1 4 2 6
*/
