#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
#define fi first
#define se second
#define pb push_back
struct path {
int x, y, lca;
ll g, s;
};
struct binS {
int lo, hi, mid;
};
const int N = 1e5+3;
const int B = (1<<17);
const int L = 17;
pair<ll, int> T[2*B+3];
pair<int, int> edg[N];
pair<int, int> price[N];
vector<int> g[N];
vector<int> mids[N];
binS bin[N];
path p[N];
int jump[N][L];
int ans[N];
int d[N];
int siz[N];
int pre[N];
int n, m, q;
int ind;
void dfs(int v, int p) {
pre[v] = ++ind;
siz[v] = 1;
d[v] = d[p]+1;
jump[v][0] = p;
for(auto u:g[v]) {
if(u == p) continue;
dfs(u, v);
siz[v] += siz[u];
}
}
int lca(int a, int b) {
if(d[a] < d[b]) swap(a, b);
for(int i=L; i>=0; i--)
if(d[jump[a][i]] >= d[b]) a = jump[a][i];
for(int i=L; i>=0; i--) {
if(jump[a][i] != jump[b][i]) {
a = jump[a][i];
b = jump[b][i];
}
}
if(a == b) return a;
return jump[a][0];
}
void clr() {
for(int i=1; i<2*B+3; i++)
T[i] = {0, 0};
}
void upd(int a, int b, int x, int v=1, int l=1, int r=B-1) {
if(l > b || r < a) return;
if(l >= a && r <= b) {
T[v].fi += x;
T[v].se += 1;
return;
}
upd(a, b, x, 2*v, l, (l+r)/2);
upd(a, b, x, 2*v+1, (l+r)/2+1, r);
}
pair<ll, int> cnt(int v) {
pair<ll, int> a = {0, 0};
v += B-1;
while(v > 0) {
a.fi += T[v].fi;
a.se += T[v].se;
v /= 2;
}
return a;
}
void parallel() {
int lft = q;
while(lft) {
clr();
for(int i=1; i<=m; i++) {
// numer krawedzi jest w price[i].se;
int curEdg = price[i].se;
int num = edg[curEdg].fi;
if(d[edg[curEdg].fi] < d[edg[curEdg].se]) num = edg[curEdg].se;
upd(pre[num], pre[num] + siz[num] - 1, price[i].fi);
for(auto x:mids[i]) {
pair<ll, int> v1 = cnt(pre[p[x].x]);
pair<ll, int> v2 = cnt(pre[p[x].y]);
pair<ll, int> lc = cnt(pre[p[x].lca]);
pair<ll, int> path = {v1.fi + v2.fi - 2*lc.fi, v1.se + v2.se - 2*lc.se};
if(p[x].s >= path.fi) {
bin[x].lo = i;
ans[x] = path.se;
}
else bin[x].hi = i-1;
bin[x].mid = (bin[x].lo + bin[x].hi + 1)/2;
if(bin[x].lo == bin[x].hi) lft--;
else mids[bin[x].mid].pb(x);
}
mids[i].clear();
mids[i].shrink_to_fit();
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> q;
for(int i=1; i<n; i++) {
cin >> edg[i].fi >> edg[i].se;
g[edg[i].fi].pb(edg[i].se);
g[edg[i].se].pb(edg[i].fi);
}
dfs(1, 0);
for(int i=1; i<=L; i++)
for(int j=1; j<=n; j++)
jump[j][i] = jump[jump[j][i-1]][i-1];
for(int i=1; i<=m; i++)
cin >> price[i].se >> price[i].fi;
sort(price+1, price+m+1);
for(int i=1; i<=q; i++) {
cin >> p[i].x >> p[i].y >> p[i].g >> p[i].s;
p[i].lca = lca(p[i].x, p[i].y);
bin[i].lo = 0;
bin[i].hi = m;
bin[i].mid = (m+1)/2;
mids[bin[i].mid].pb(i);
}
parallel();
for(int i=1; i<=q; i++) {
pair<ll, int> v1 = cnt(pre[p[i].x]);
pair<ll, int> v2 = cnt(pre[p[i].y]);
pair<ll, int> lc = cnt(pre[p[i].lca]);
pair<ll, int> path = {v1.fi + v2.fi - 2*lc.fi, v1.se + v2.se - 2*lc.se};
int Ans = p[i].g - (path.se - ans[i]);
cout << max(Ans, -1) << endl;
}
}
