#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
#define int ll
const int K = 19;
struct BIT{
int n;
vector<ll> sm;
BIT(int _n){
n = _n;
sm.resize(n);
}
void add(int in, ll x){
in++;
while(in <= n) sm[in-1]+=x, in+=in&-in;
}
void add(int l, int r, ll x){
add(l, x);
if(r+1 < n) add(r+1, -x);
}
ll get(int in){
in++;
ll s = 0;
while(in >= 1) s+=sm[in-1], in-=in&-in;
return s;
}
};
struct query{
int a, b, c;
ll g, s;
int i;
query(){}
query(int _a, int _b, int _c, ll _g, ll _s, int _i): a(_a), b(_b), c(_c), g(_g), s(_s), i(_i) {}
};
int n, m, q;
vector<pair<int, ll>> c;
vector<vector<int>> tree;
vector<int> depth, pos, sz;
vector<int> anc[K];
BIT bit1(0), bit2(0);
vector<ll> ans;
vector<pair<int, int>> edges;
vector<query> Q;
int intime = 0;
void dfs(int nd, int ss, int d){
pos[nd] = intime++;
depth[nd] = d;
if(ss != -1) anc[0][nd] = ss;
for(int x: tree[nd]) if(x != ss) dfs(x, nd, d+1), sz[nd]+=sz[x];
}
int get_anc(int nd, int d){
for(int i = 0; i < K; i++){
if(d&1) nd = anc[i][nd];
d>>=1;
}
return nd;
}
int lca(int a, int b){
if(depth[a] > depth[b]) swap(a, b);
b = get_anc(b, depth[b]-depth[a]);
if(a == b) return a;
for(int i = K-1; i >= 0; i--) if(anc[i][a] != anc[i][b])
a = anc[i][a], b = anc[i][b];
return anc[0][a];
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, m, q; cin >> n >> m >> q;
c.resize(m);
tree.resize(n);
depth.resize(n);
pos.resize(n);
sz.assign(n, 1);
fill(anc, anc+K, vector<int>(n, 0));
bit1 = BIT(n), bit2 = BIT(n);
ans.resize(q);
for(int i = 0; i < n-1; i++){
int a, b; cin >> a >> b; a--, b--;
tree[a].pb(b);
tree[b].pb(a);
edges.pb({a, b});
}
dfs(0, -1, 0);
for(int p = 1; p < K; p++) for(int i = 0; i < n; i++)
anc[p][i] = anc[p-1][anc[p-1][i]];
for(auto &[i, x]: c){
cin >> i >> x, i--;
auto [a, b] = edges[i];
if(depth[a] > depth[b]) i = a;
else i = b;
bit1.add(pos[i], pos[i]+sz[i]-1, x);
}
sort(c.begin(), c.end(), [](pair<int, ll> a, pair<int, ll> b){
return make_pair(a.sc, a.f) > make_pair(b.sc, b.f);
});
c.insert(c.begin(), {0, 0});
for(int i = 0; i < q; i++){
int a, b; ll g, s; cin >> a >> b >> g >> s;
a--, b--;
int c = lca(a, b);
a = pos[a], b = pos[b], c = pos[c];
Q.pb(query(a, b, c, g, s, i));
}
function<void(int, int, vector<int>)> pbs = [&](int l, int r, const vector<int>& Qi){
if(Qi.empty()) return;
if(l == r){
bit2.add(pos[c[l].f], pos[c[l].f]+sz[c[l].f]-1, 1);
for(int i: Qi){
ans[Q[i].i] = Q[i].g-bit2.get(Q[i].a)-bit2.get(Q[i].b)+bit2.get(Q[i].c)*2;
ans[Q[i].i] = max(ans[Q[i].i], -1LL);
}
bit2.add(pos[c[l].f], pos[c[l].f]+sz[c[l].f]-1, -1);
return;
}
int md = (l+r)/2;
for(int i = l; i <= md; i++){
bit1.add(pos[c[i].f], pos[c[i].f]+sz[c[i].f]-1, -c[i].sc);
bit2.add(pos[c[i].f], pos[c[i].f]+sz[c[i].f]-1, 1);
}
vector<int> A, B;
for(int i: Qi){
if(bit1.get(Q[i].a)+bit1.get(Q[i].b)-bit1.get(Q[i].c)*2 > Q[i].s) B.pb(i);
else A.pb(i);
}
pbs(md+1, r, B);
for(int i = l; i <= md; i++){
bit1.add(pos[c[i].f], pos[c[i].f]+sz[c[i].f]-1, c[i].sc);
bit2.add(pos[c[i].f], pos[c[i].f]+sz[c[i].f]-1, -1);
}
pbs(l, md, A);
};
vector<int> Qi;
for(int i = 0; i < q; i++) Qi.pb(i);
pbs(0, m, Qi);
for(ll x: ans) cout << x << "\n";
}
