#include <bits/stdc++.h>
#define all(v) begin(v), end(v)
#define ii pair<int, int>
#define fi first
#define se second
#define siz(v) (int)(v).size()
#define ii pair<int, int>
#define lli pair<long long, int>
#define dbg(x) "[" #x " = " << x << "]"
#define MASK(i) (1LL << (i))
using namespace std;
const int MAXN = 1e5 + 5, infINT = 1e9 + 132123, mod = 998244353, LOG = 18;
const long long inf = 1e18 + 123;
void add(int &a, const int &b){
a += b;
if (a >= mod) a -= mod;
}
void sub(int &a, const int &b){
a -= b;
if (a < 0) a += mod;
}
int mul(const int &a, const int &b){
return 1LL * a * 1LL * b % mod;
}
int bin_pow(int a, int k){
int res = 1;
while(k){
if (k & 1) res = mul(res, a);
k >>= 1; a = mul(a, a);
}
return res;
}
template<typename T> struct fenwickTree{
int n;
vector<T > bit;
fenwickTree(int _n = 0): n(_n){
bit.assign(n + 1, 0);
}
void update(int pos, const T &delta){
for(; pos <= n; pos += pos & -pos) bit[pos] += delta;
}
T get(int pos){
T sum = 0;
for(; pos > 0; pos ^= pos & -pos) sum += bit[pos];
return sum;
}
void update(int l, int r, const int &delta){
if (l > r) return;
update(l, +delta);
update(r + 1, -delta);
}
T get(int l, int r){
if (l > r) return 0;
return get(r) - get(l - 1);
}
};
struct Q{
int u, v, x;
long long y;
Q(int _u = 0, int _v = 0, int _x = 0, long long _y = 0):
u(_u), v(_v), x(_x), y(_y) {};
};
int numNode, numPos, numQuery, l[MAXN], r[MAXN], m[MAXN], sta[MAXN], fin[MAXN];
int st[LOG][MAXN << 1], tour[MAXN << 1], h[MAXN], rtour[MAXN], cnt[MAXN], res[MAXN];
long long sumCost[MAXN];
vector<int > adj[MAXN], mid[MAXN];
vector<ii > pos;
Q query[MAXN];
fenwickTree<int > bitCnt;
fenwickTree<long long > bitSum;
struct E{
int u, v;
E(int _u = 0, int _v = 0):
u(_u), v(_v) {};
int other(int x){
return u ^ v ^ x;
}
int high(){
return h[u] > h[v] ? u: v;
}
};
E edge[MAXN];
void input(){
cin >> numNode >> numPos >> numQuery;
for(int i = 1; i < numNode; i++){
int u, v; cin >> u >> v;
adj[u].push_back(i);
adj[v].push_back(i);
edge[i] = E(u, v);
}
for(int i = 1; i <= numPos; i++){
int p, c; cin >> p >> c;
pos.emplace_back(c, p);
}
for(int q = 1; q <= numQuery; q++){
int u, v, x;
long long y;
cin >> u >> v >> x >> y;
query[q] = Q(u, v, x, y);
}
}
void dfs(int u, int par = 0){
tour[++tour[0]] = u;
rtour[u] = tour[0];
sta[u] = ++sta[0];
for(int id: adj[u]) if (id != par) {
int v = edge[id].other(u);
h[v] = h[u] + 1;
dfs(v, id);
tour[++tour[0]] = u;
}
fin[u] = sta[0];
}
#define minHeight(a, b) (h[a] < h[b] ? a: b)
int lca(int u, int v){
int l = rtour[u], r = rtour[v];
if (l > r) swap(l, r);
int k = __lg(r - l + 1);
return minHeight(st[k][l], st[k][r - MASK(k) + 1]);
}
int getCnt(int u, int v){
return bitCnt.get(sta[u]) + bitCnt.get(sta[v]) - 2 * bitCnt.get(sta[lca(u, v)]);
}
long long getSum(int u, int v){
return bitSum.get(sta[u]) + bitSum.get(sta[v]) - 2 * bitSum.get(sta[lca(u, v)]);
}
void solve(){
sort(all(pos));
pos.emplace_back(infINT, numNode + 1);
dfs(1);
for(int i = 1; i <= tour[0]; i++) st[0][i] = tour[i];
for(int j = 1; j < LOG; j++)
for(int i = 1; i + MASK(j - 1) - 1 <= tour[0]; i++){
st[j][i] = minHeight(st[j - 1][i], st[j - 1][i + MASK(j - 1)]);
}
for(int q = 1; q <= numQuery; q++){
l[q] = 0, r[q] = siz(pos) - 1;
}
fenwickTree<long long > bitSta(numNode);
for(int i = 0; i < siz(pos); i++){
int u = edge[pos[i].se].high(), w = pos[i].fi;
bitSta.update(sta[u], fin[u], +w);
}
memset(res, -1, sizeof res);
// for(int i = 1; i <= numNode; i++) cout << sta[i] << ' '; cout << '\n';
// for(int u = 1; u <= numNode; u++) cout << bitSta.get(sta[u]) << ' '; cout << '\n';
int tmp = 0;
while(true){
bool flag = 0;
// cout << "LOOP " << (++tmp) << ": \n";
for(int q = 1; q <= numQuery; q++) if (l[q] <= r[q]){
m[q] = (l[q] + r[q]) >> 1;
flag = 1;
mid[m[q]].push_back(q);
// cout << dbg(q) << dbg(m[q]) << '\n';
}
if (!flag) break;
bitCnt = fenwickTree<int >(numNode);
bitSum = bitSta;
for(int i = siz(pos) - 1; i >= 0; i--){
// cout << "I " << i << ": \n";
int u = edge[pos[i].se].high(), w = pos[i].fi;
bitSum.update(sta[u], fin[u], -w);
bitCnt.update(sta[u], fin[u], +1);
// for(int u = 1; u <= numNode; u++) cout << bitCnt.get(sta[u]) << ' '; cout << '\n';
// for(int u = 1; u <= numNode; u++) cout << bitSum.get(sta[u]) << ' '; cout << '\n';
for(int id: mid[i]){
int u = query[id].u, v = query[id].v, x = query[id].x;
long long y = query[id].y;
sumCost[id] = getSum(u, v);
cnt[id] = getCnt(u, v);
// cout << "ANS " << u << ' ' << v << ": " << sumCost[id] << ' ' << cnt[id] << '\n';
}
}
for(int q = 1; q <= numQuery; q++) if (l[q] <= r[q]){
if (sumCost[q] <= query[q].y){
res[q] = cnt[q];
l[q] = m[q] + 1;
}else{
r[q] = m[q] - 1;
}
mid[m[q]].clear();
}
}
for(int q = 1; q <= numQuery; q++) cout << max(-1, query[q].x - res[q]) << '\n';
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define task "test"
if (fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
input();
solve();
cerr << (1.0 * clock()) / CLOCKS_PER_SEC << ".s\n";
}
