/* 29 . 03 . 2008 */
#include <bits/stdc++.h>
using namespace std ;
typedef long long ll ;
typedef vector<int> vi ;
typedef vector<pair<int,int>> vii ;
typedef pair<int,int> pii ;
typedef pair<ll,int> pli ;
typedef pair<int,ll> pil ;
typedef pair<ll,ll> pll ;
#define FOR(i,a,b) for(int i(a) ; i <= (int)b ; i++)
#define FORD(i,a,b) for(int i(a) ; i >= (int)b ; i--)
#define FORN(i,a,b) for(int i(a) ; i < (int)b ; i++)
#define all(a) a.begin() , a.end()
#define pb push_back
#define fi first
#define se second
#define endl '\n'
#define BIT(mask,i) ((mask>>i)&1)
#define builtin_popcount builtin_popcountll
#define MASK(a) (1ll << a)
template <class T> bool maxi(T &x,T y) { if (x < y) { x = y ; return true ;} return false ;}
template <class T> bool mini(T &x,T y) { if (x > y) { x = y ; return true ;} return false ;}
const int N = 1e5 + 5 ;
int n, m, q ;
struct Edges {
int u, v ;
ll w ;
} e[N] ;
struct Queries {
int st, ed ;
ll w1, w2 ;
} Q[N] ;
struct Station {
int id; ll val ;
} sta[N] ;
vector <pil> g[N] ;
void init() {
cin >> n >> m >> q ;
FOR(i, 1, n - 1) {
int u, v ; cin >> u >> v ;
e[i] = {u, v, 0} ;
}
FOR(i, 1, m) {
int p, c ; cin >> p >> c ;
sta[i] = {p , c} ;
e[p].w+= c ;
}
FOR(i, 1, n - 1) {
g[e[i].u].pb({e[i].v, e[i].w}) ; g[e[i].v].pb({e[i].u, e[i].w}) ;
}
FOR(i, 1, q) {
int st, ed ; ll w1, w2 ; cin >> st >> ed >> w1 >> w2 ;
Q[i] = {st, ed, w1, w2} ;
}
}
struct HeavyLightDecomposition {
int par[N], head[N], sz[N], cur[N], pos[N], arr[N], h[N] ;
ll val[N] ;
void dfs_sz(int u) {
sz[u] = 1 ;
for(pil x : g[u]) {
int v = x.fi; ll w = x.se ;
if(v == par[u]) continue ;
par[v] = u ;
h[v] = h[u] + 1 ;
val[v] = w ;
dfs_sz(v);
sz[u]+= sz[v] ;
}
}
int crt, timeDFS ;
void dfs_hld(int u) {
if(!head[crt]) head[crt] = u ;
pos[u] = ++ timeDFS ;
arr[pos[u]] = u ;
cur[u] = crt ;
int nxt = - 1 ;
for(pil x : g[u]) {
int v = x.fi ;
if(v == par[u]) continue ;
if(nxt == -1 || sz[v] > sz[nxt]) nxt = v ;
}
if(nxt != - 1) dfs_hld(nxt) ;
for(pil x : g[u]) {
int v = x.fi ;
if(v == par[u] || v==nxt) continue ;
crt++ ;
dfs_hld(v) ;
}
}
ll bit[N][3] ;
void up(int u, ll val, int t) {
for(int i = u; i <= n ; i+=i&-i) bit[i][t]+= val ;
}
ll get(int u, int t) {
ll sum = 0 ;
for(int i = u ; i ; i-=i&-i) sum+= bit[i][t] ;
return sum ;
}
ll get(int l, int r, int t) {
return get(r, t) - get(l - 1, t) ;
}
int lca(int u, int v) {
while(cur[u] != cur[v]) {
if(cur[u] > cur[v]) u = par[head[cur[u]]] ;
else v = par[head[cur[v]]] ;
}
if(h[u] < h[v]) return u ;
else return v ;
}
ll SUMPATH(int u, int v, int t) {
int p = lca(u, v) ;
ll res = 0 ;
while(cur[u]!=cur[p]) {
res+= get(pos[head[cur[u]]], pos[u], t) ;
u = par[head[cur[u]]] ;
}
while(cur[v]!=cur[p]) {
res+= get(pos[head[cur[v]]], pos[v], t) ;
v = par[head[cur[v]]] ;
}
if(pos[u] < pos[v]) res+= get(pos[u] + 1, pos[v], t) ;
else if(pos[v] < pos[u]) res+= get(pos[v] + 1, pos[u], t) ;
return res ;
}
void init() {
dfs_sz(1) ; dfs_hld(1) ;
}
void reset() {
memset(bit, 0, sizeof bit) ;
}
} hld ;
ll L[N], R[N], ans[N] ;
vi Quer[N] ;
void solve() {
hld.init() ;
sort(sta + 1, sta + 1 + m, [](Station u, Station v) {
return u.val < v.val ;
}) ;
memset(ans, 0x3f, sizeof ans) ;
FOR(i, 1, q) L[i] = 0, R[i] = m ;
FOR(i, 1, m) {
int u = e[sta[i].id].u, v = e[sta[i].id].v ;
if(v == hld.par[u]) swap(e[sta[i].id].u, e[sta[i].id].v) ;
// cout << u << ' ' << v << endl ;
}
while(1) {
hld.reset() ;
FOR(i, 1, m) Quer[i].clear() ;
bool ok = false ;
FOR(i, 1, q) if(L[i] <= R[i]) {
ok = true ;
Quer[(L[i] + R[i])/2].pb(i) ;
}
if(!ok) break ;
FOR(i, 1, m) {
int v = e[sta[i].id].v ;
hld.up(hld.pos[v], 1, 1) ;
}
FOR(i, 0, m) {
if(i > 0) {
ll w = sta[i].val ;
int v = e[sta[i].id].v ;
hld.up(hld.pos[v], -1, 1) ;
hld.up(hld.pos[v], w, 2) ;
}
for(int id : Quer[i]) {
int u = Q[id].st, v = Q[id].ed ; ll silver = Q[id].w2 ;
if(hld.SUMPATH(u, v, 2) <= silver) {
ans[id] = hld.SUMPATH(u, v, 1) ;
L[id] = i + 1 ;
} else {
R[id] = i - 1 ;
}
}
}
}
FOR(i, 1, q) cout << max(Q[i].w1- ans[i], 1ll * -1) << endl ;
}
signed main() {
#define task ""
ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0) ;
if(fopen(".inp","r")) {
freopen(".inp","r",stdin) ; freopen(".out","w",stdout) ;
}
if(fopen(task".inp","r")) {
freopen(task".inp","r",stdin) ; freopen(task".out","w",stdout) ;
}
init() ;
solve() ;
cerr << "\nTime : " << clock() * 0.001 << "s" << endl ;
return 0 ;
}
/* Watbor */
