#include <cstdio>
#include <vector>
#include <algorithm>
#define X first
#define Y second
#define PB push_back
using namespace std;
typedef long long ll;
typedef pair<int, ll> pil;
const int LOG = 17;
const int N = 1 << LOG;
struct node {
node *l, *r;
int cnt;
ll upd;
node() : l(NULL), r(NULL), cnt(0), upd(0) {}
node(node *l, node *r, int cnt, ll upd) : l(l), r(r), cnt(cnt), upd(upd) {}
};
typedef node* pnode;
int GET;
node T[3 * LOG * N];
pnode get(pnode u = NULL) {
if(u != NULL) {
T[GET].l = u->l;
T[GET].r = u->r;
T[GET].cnt = u->cnt;
T[GET].upd = u->upd;
}
return &T[GET++];
}
pnode update(int l, int r, ll val, pnode u = NULL, int lo = 0, int hi = N) {
if(r <= lo || hi <= l) return u;
if(l <= lo && hi <= r) {
pnode v = get(u);
v->cnt += 1;
v->upd += val;
return v;
}
pnode v = get(u);
int mi = (lo + hi) / 2;
if(u->l == NULL) u->l = get();
if(u->r == NULL) u->r = get();
v->l = update(l, r, val, u->l, lo, mi);
v->r = update(l, r, val, u->r, mi, hi);
return v;
}
int IV[N], MR[N], mrv;
int UP[N][LOG], DEP[N];
vector<int> G[N];
pil query(int x, pnode u, int lo = 0, int hi = N) {
if(u == NULL) return {0, 0};
if(lo + 1 == hi) return {u->cnt, u->upd};
int mi = (lo + hi) / 2;
pil res = IV[x] < mi ? query(x, u->l, lo, mi) : query(x, u->r, mi, hi);
return {res.X + u->cnt, res.Y + u->upd};
}
void dfs(int u, int p) { // DEP[1] = 1 !!!
IV[u] = mrv++;
for(int v : G[u])
if(v != p) {
DEP[v] = DEP[u] + 1;
UP[v][0] = u;
dfs(v, u);
}
MR[u] = mrv;
}
int lca(int u, int v) {
if(DEP[u] > DEP[v]) swap(u, v);
for(int i = LOG - 1; i >= 0; --i)
if(DEP[UP[v][i]] >= DEP[u]) v = UP[v][i];
if(u == v) return u;
for(int i = LOG - 1; i >= 0; --i)
if(UP[u][i] != UP[v][i]) {
u = UP[u][i];
v = UP[v][i];
}
return UP[u][0];
}
int A[N], B[N], P[N], C[N];
int I[N];
pnode RT[N];
pil query_path(int u, int v, int anc, int t) {
pil ru = query(u, RT[t]), rv = query(v, RT[t]), ranc = query(anc, RT[t]);
return {ru.X + rv.X - 2 * ranc.X, ru.Y + rv.Y - 2 * ranc.Y};
}
int main() {
int n, m, q;
scanf("%d%d%d", &n, &m, &q);
for(int i = 0; i < n - 1; ++i) {
scanf("%d%d", A + i, B + i);
G[A[i]].PB(B[i]);
G[B[i]].PB(A[i]);
}
for(int i = 1; i <= m; ++i) {
I[i] = i;
scanf("%d%d", P + i, C + i);
--P[i];
}
sort(I + 1, I + m + 1, [&](int a, int b) { return C[a] < C[b]; });
DEP[1] = 1;
dfs(1, 0);
RT[0] = get();
for(int i = 1; i <= m; ++i) {
int ind = I[i], p = P[ind], u = (DEP[A[p]] < DEP[B[p]] ? B[p] : A[p]);
RT[i] = update(IV[u], MR[u], C[ind], RT[i - 1]);
// printf("! %d[%d, %d] + %d\n", u, IV[u], MR[u], C[ind]);
}
for(; q--; ) {
int s, t, x;
ll y;
scanf("%d%d%d%lld", &s, &t, &x, &y);
int a = lca(s, t), lo = -1, hi = m + 1;
for(; hi - lo > 1; ) {
int mi = (lo + hi) / 2;
pil res = query_path(s, t, a, mi);
// if(q == 1) printf("%d: %d %lld\n", mi, res.X, res.Y);
if(res.Y > y) hi = mi;
else lo = mi;
}
pil res = query_path(s, t, a, lo), res_ = query_path(s, t, a, m);
// printf("%d %d %d | %d\n", s, t, a, lo);
printf("%d\n", max(-1, x - (res_.X - res.X)));
}
return 0;
}
