#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll,ll>
#define mp make_pair
#define pb push_back
#define BIT(x,i) (((x)>>(i))&1)
#define MASK(i) (1LL<<(i))
template<typename T1, typename T2> bool minimize(T1 &a, T2 b)
{if(a>b) a=b; else return 0; return 1;}
template<typename T1, typename T2> bool maximize(T1 &a, T2 b)
{if(a<b) a=b; else return 0; return 1;}
#define file "task"
const int maxn = 1e5 + 5;
const int MOD = 1e9 + 7;
const int oo = 1e9;
const ll OO = 1e18;
const int LOG = 19;
int n, m, q;
int timeDfs;
int l[maxn];
int r[maxn];
int h[maxn];
int f[maxn];
pii p[maxn];
int st[maxn];
int en[maxn];
int ans[maxn];
int up[maxn][LOG + 2];
pii edge[maxn];
int check[maxn];
vector<pii> g[maxn];
vector<int> tmp[maxn];
struct fenwick{
ll fw[maxn];
fenwick(){
memset(fw, 0, sizeof(fw));
}
void update(int id, int val){
for(;id <= n; id += id & -id) fw[id] += val;
}
void update(int l, int r, int val){
update(l, val);
update(r + 1, -val);
}
ll get(int id){
ll ret = 0;
for(;id > 0; id -= id & -id) ret += fw[id];
return ret;
}
} bit1, bit2;
struct item{
int u, v, ancestor;
ll gold, silver;
item(){}
item(int u, int v, int ancestor, ll gold, ll silver) :
u(u), v(v), ancestor(ancestor), gold(gold), silver(silver){}
} query[maxn];
void input(){
cin >> n >> m >> q;
for(int i = 1; i <= n - 1; i++){
int u, v; cin >> u >> v;
g[u].pb(mp(v, i));
g[v].pb(mp(u, i));
edge[i] = mp(u, v);
}
for(int i = 1; i <= m; i++){
int id, w; cin >> id >> w;
check[id]++;
p[i] = mp(w, id);
}
}
void dfs(int u, int dad){
st[u] = ++timeDfs;
for(auto [v, id] : g[u]){
if(v == dad) continue;
h[v] = h[u] + 1;
f[v] = f[u] + check[id];
up[v][0] = u;
for(int i = 1; i <= LOG; i++)
up[v][i] = up[up[v][i - 1]][i - 1];
dfs(v, u);
}
en[u] = timeDfs;
}
int lca(int u, int v){
if(h[u] < h[v]) swap(u, v);
for(int i = LOG; i >= 0; i--)
if(h[u] - MASK(i) >= h[v])
u = up[u][i];
if(u == v) return u;
for(int i = LOG; i >= 0; i--)
if(up[u][i] != up[v][i])
u = up[u][i], v = up[v][i];
return up[u][0];
}
void proc(){
dfs(1, 1);
sort(p + 1, p + 1 + m);
for(int i = 1; i <= q; i++){
int u, v; ll gold, silver;
cin >> u >> v >> gold >> silver;
query[i] = item(u, v, lca(u, v), gold, silver);
l[i] = 1; r[i] = m;
}
for(int i = 1; i <= m; i++){
auto [w, id] = p[i];
auto &[u, v] = edge[id];
if(h[u] > h[v]) swap(u, v);
}
while(1){
bool ok = 1;
for(int i = 1; i <= q; i++){
if(l[i] > r[i]) continue;
int mid = (l[i] + r[i]) / 2;
tmp[mid].pb(i);
ok = 0;
}
if(ok) break;
bit1 = bit2 = fenwick();
for(int i = 1; i <= m; i++){
auto [w, id] = p[i];
auto [u, v] = edge[id];
bit1.update(st[v], en[v], w);
bit2.update(st[v], en[v], 1);
for(int idx : tmp[i]){
auto [u, v, ancestor, gold, silver] = query[idx];
ll sum = bit1.get(st[u]) + bit1.get(st[v]) - 2LL * bit1.get(st[ancestor]);
if(sum <= silver){
l[idx] = i + 1;
ans[idx] = bit2.get(st[u]) + bit2.get(st[v]) - 2LL * bit2.get(st[ancestor]);
} else {
r[idx] = i - 1;
}
}
tmp[i].clear();
}
}
for(int i = 1; i <= q; i++){
auto [u, v, ancestor, gold, silver] = query[i];
int sum = f[u] + f[v] - 2 * f[lca(u, v)];
if(gold >= sum - ans[i]){
cout << gold - (sum - ans[i]) << '\n';
} else {
cout << -1 << '\n';
}
}
}
signed main(){
cin.tie(nullptr)->sync_with_stdio(0); cout.tie(nullptr);
if(fopen(file".inp", "r")){
freopen(file".inp", "r", stdin);
freopen(file".out", "w", stdout);
}
input();
proc();
return 0;
}
