#include <bits/stdc++.h>
using namespace std;
using ll = long long; using pii = pair<ll,ll>;
const ll Nm = 1e5+5; const ll E = 18;
const ll INF = 1e18;
struct Node {
//map<ll,ll> m0; //cost->number
//map<ll,pii> mps; //aggregate: cost -> {# <=cost, val <=cost}
vector<pii> m0;
vector<array<ll,3>> mps;
ll ncp = 0;
void prc() {
ll n0=0; ll v0=0;
//mps[-INF]={0,0};
mps.push_back({-INF,0LL,0LL});
for (pii p0: m0) {
ll c1 = p0.first; ll n1 = p0.second;
n0+=n1; v0+=n1*c1;
//mps[c1]={n0,v0};
mps.push_back({c1,n0,v0});
}
}
Node(){}
Node(vector<ll> v1) {
map<ll,ll> mtest;
for (ll x: v1) {
mtest[x]++;
}
ncp = v1.size();
for (pii p0: mtest) {
m0.push_back(p0);
}
prc();
}
Node(Node n1, Node n2) {
map<ll,ll> mtest;
for (pii p0: n1.m0) {
mtest[p0.first]+=p0.second;
}
for (pii p0: n2.m0) {
mtest[p0.first]+=p0.second;
}
ncp = n1.ncp+n2.ncp;
for (pii p0: mtest) {
m0.push_back(p0);
}
prc();
}
pii qry(ll x) {
auto A0 = --upper_bound(mps.begin(),mps.end(),(array<ll,3>){x,INF,INF});
return {(*A0)[1],(*A0)[2]};
}
};
ll bjump[Nm][E];
Node ejump[Nm][E];
pii ett[Nm][E];
vector<pii> adj[Nm];
vector<ll> fadj[Nm];
ll radj[Nm];
ll locr[Nm]; //location of road (aka location of child)
ll ht[Nm];
ll floc[Nm];
inline ll gp(ll x, ll e) {
if (x<0) {
return x;
}
return bjump[x][e];
}
inline pii fz(pii p1, pii p2) {
if (p1.second<p2.second) {
return p1;
} else {
return p2;
}
}
inline ll l2(ll x) {
return (31-__builtin_clz(x));
}
inline ll v2(ll x) {
return __builtin_ctz(x);
}
ll lca(ll x, ll y) {
x = floc[x]; y = floc[y];
if (x>y) {
swap(x,y);
}
ll lv = l2(y-x+1);
return (fz(ett[x][lv],ett[y-(1<<lv)+1][lv]).first);
}
pii ginf(vector<Node*>& v1, ll cst) {
pii vf = {0,0};
for (auto A0: v1) {
pii v2 = A0->qry(cst);
vf = {vf.first+v2.first,vf.second+v2.second};
}
return vf; //{number, total cost}
}
ll qry(vector<Node*>& v1, ll y) {
ll xmin = 0; ll xmax = 1e10;
//first binary search for the largest value of xtest
//for which ginf(xtest).second <= y
//store pair at this value
while (xmin < xmax) {
ll xtest = (xmin+xmax+1)/2;
if ((ginf(v1,xtest).second)<=y) {
xmin = xtest;
} else {
xmax = xtest-1;
}
}
pii p1 = ginf(v1,xmin);
pii p2 = ginf(v1,xmin+1);
if (p1.first==p2.first || p1.second==y) {
return p1.first;
} else {
ll vext = y-p1.second;
ll cst = (p2.second-p1.second)/(p2.first-p1.first);
//assert(cst==(xmin+1));
return (p1.first+vext/cst);
}
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
ll N,M,Q; cin >> N >> M >> Q;
for (ll i=0;i<(N-1);i++) {
ll a,b; cin >> a >> b;
a--; b--;
adj[a].push_back({b,i});
adj[b].push_back({a,i});
}
radj[0]=-1;
ht[0]=0;
queue<ll> q0;
q0.push(0);
while (!q0.empty()) {
ll x = q0.front(); q0.pop();
for (pii p0: adj[x]) {
ll y = p0.first;
if (y != radj[x]) {
fadj[x].push_back(y);
radj[y]=x;
locr[p0.second]=y;
q0.push(y);
ht[y]=1+ht[x];
}
}
}
vector<ll> ettv;
stack<pii> st0;
st0.push({0,0});
while (!st0.empty()) {
pii p0 = st0.top(); st0.pop();
ll x = p0.first; ll t = p0.second;
ettv.push_back(x);
if (t==0) {
floc[x]=ettv.size()-1;
for (ll y: fadj[x]) {
st0.push({x,1});
st0.push({y,0});
}
}
}
for (ll i=0;i<ettv.size();i++) {
ett[i][0]={ettv[i],ht[ettv[i]]};
}
for (ll e=1;e<E;e++) {
for (ll i=0;i<=(Nm-(1<<e));i++) {
ett[i][e]=fz(ett[i][e-1],ett[i+(1<<(e-1))][e-1]);
}
}
vector<ll> costE[Nm];
for (ll m=0;m<M;m++) {
ll p,c; cin >> p >> c;
p--;
costE[locr[p]].push_back(c);
}
for (ll i=0;i<N;i++) {
bjump[i][0]=radj[i];
ejump[i][0]=Node(costE[i]);
}
if (N<=2000) {
for (ll e=1;e<E;e++) {
for (ll i=0;i<N;i++) {
if (bjump[i][e-1]==-1) {
bjump[i][e]=bjump[i][e-1];
ejump[i][e]=ejump[i][e-1];
} else {
bjump[i][e]=bjump[bjump[i][e-1]][e-1];
ejump[i][e]=Node(ejump[i][e-1],ejump[bjump[i][e-1]][e-1]);
}
}
}
} else {
exit(0);
}
for (ll q=0;q<Q;q++) {
ll s,t,x,y; cin >> s >> t >> x >> y;
s--; t--;
if (s==t) {
cout << x << "\n"; continue;
}
//exit(0);
ll lc = lca(s,t);
//cout << "lc="<<lc<<"\n"; exit(0);
//cout << "lca of s,t="<<s<<","<<t<<" is "<<lc<<"\n";
//ll dist0 = ht[s]+ht[t]-2*ht[lc];
vector<Node*> vq;
ll ntoll = 0;
while (s != lc) {
ll dht = ht[s]-ht[lc];
ll ldh = l2(dht);
vq.push_back(&ejump[s][ldh]);
ntoll += ejump[s][ldh].ncp;
s=bjump[s][ldh];
}
while (t != lc) {
ll dht = ht[t]-ht[lc];
ll ldh = l2(dht);
vq.push_back(&ejump[t][ldh]);
ntoll += ejump[t][ldh].ncp;
t=bjump[t][ldh];
}
ll maxr = qry(vq,y);
ll gused = max(0LL,ntoll-maxr);
//cout << "ntoll,maxr="<<ntoll<<","<<maxr<<"\n";
if (x<gused) {
cout << "-1\n";
} else {
cout << (x-gused) <<"\n";
}
// cout << "maxr="<<maxr<<"\n";
// cout << "dist0="<<dist0<<"\n";
// if ((maxr+x)>=dist0) {
// cout << (maxr+x-dist0) <<"\n";
// } else {
// cout << "-1\n";
// }
}
}
