#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define taskname ""
using namespace std;
const int MAXN = 200000 + 5;
const int LOG = 20;
int n, m, q;
vector<pair<int,int>> adj[MAXN];
vector<int> costsOnEdge[MAXN];
int parentUp[LOG][MAXN];
int depthArr[MAXN];
int rootPST[MAXN];
struct Node { int l, r; int cnt; ll sum; } seg[5000000];
int nxtNode = 1;
vector<int> comp;
int K;
int updatePST(int prev, int l, int r, int pos){
int cur = nxtNode++;
seg[cur] = seg[prev];
seg[cur].cnt += 1;
seg[cur].sum += comp[pos-1];
if(l < r){
int mid = (l + r) >> 1;
if(pos <= mid) seg[cur].l = updatePST(seg[prev].l, l, mid, pos);
else seg[cur].r = updatePST(seg[prev].r, mid+1, r, pos);
}
return cur;
}
int dfs_build(int u, int p){
parentUp[0][u] = p;
for(auto &pr : adj[u]){
int v = pr.fi;
int ei = pr.se;
if(v == p) continue;
depthArr[v] = depthArr[u] + 1;
int curRoot = rootPST[u];
for(int c : costsOnEdge[ei]){
int idx = int(lower_bound(comp.begin(), comp.end(), c) - comp.begin()) + 1;
curRoot = updatePST(curRoot, 1, K, idx);
}
rootPST[v] = curRoot;
dfs_build(v, u);
}
return 0;
}
int lca(int u, int v){
if(depthArr[u] < depthArr[v]) swap(u, v);
int diff = depthArr[u] - depthArr[v];
for(int i = 0; i < LOG; i++){
if(diff & (1<<i)) u = parentUp[i][u];
}
if(u == v) return u;
for(int i = LOG-1; i >= 0; i--){
if(parentUp[i][u] != parentUp[i][v]){
u = parentUp[i][u];
v = parentUp[i][v];
}
}
return parentUp[0][u];
}
ll cntNode(int x){ return seg[x].cnt; }
ll sumNode(int x){ return seg[x].sum; }
ll querySilver(int ru, int rv, int rlca, ll &Y, int l, int r){
if(!ru && !rv && !rlca) return 0;
if(l == r){
ll cntLeft = cntNode(seg[ru].l) + cntNode(seg[rv].l) - 2LL*cntNode(seg[rlca].l);
ll cost = comp[l-1];
ll take = min(cntLeft, Y / cost);
Y -= take * cost;
return take;
}
int mid = (l + r) >> 1;
int lu = seg[ru].l, lv = seg[rv].l, llca = seg[rlca].l;
ll cntLeft = cntNode(lu) + cntNode(lv) - 2LL*cntNode(llca);
ll sumLeft = sumNode(lu) + sumNode(lv) - 2LL*sumNode(llca);
if(sumLeft <= Y){
Y -= sumLeft;
ll takeLeft = cntLeft;
int ruR = seg[ru].r, rvR = seg[rv].r, rlcaR = seg[rlca].r;
return takeLeft + querySilver(ruR, rvR, rlcaR, Y, mid+1, r);
} else {
int ruL = seg[ru].l, rvL = seg[rv].l, rlcaL = seg[rlca].l;
return querySilver(ruL, rvL, rlcaL, Y, l, mid);
}
}
int main(){
if(fopen(taskname".inp","r")){
freopen(taskname".inp","r", stdin);
freopen(taskname".out","w", stdout);
}
ios::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m >> q;
vector<pair<int,int>> edges(n);
for(int i = 1; i < n; i++){
int u,v;
cin >> u >> v;
adj[u].pb({v, i});
adj[v].pb({u, i});
edges[i] = {u,v};
}
vector<pair<int,int>> checkpoints(m+1);
for(int j = 1; j <= m; j++){
int pj, cj;
cin >> pj >> cj;
checkpoints[j] = {pj, cj};
costsOnEdge[pj].pb(cj);
comp.pb(cj);
}
sort(comp.begin(), comp.end());
comp.erase(unique(comp.begin(), comp.end()), comp.end());
K = comp.size();
rootPST[1] = 0;
depthArr[1] = 0;
dfs_build(1, 1);
for(int i = 1; i < LOG; i++){
for(int u = 1; u <= n; u++){
parentUp[i][u] = parentUp[i-1][ parentUp[i-1][u] ];
}
}
while(q--){
int s,t;
ll X,Y;
cin >> s >> t >> X >> Y;
int w = lca(s,t);
ll totalCnt = cntNode(rootPST[s]) + cntNode(rootPST[t]) - 2LL*cntNode(rootPST[w]);
ll remY = Y;
ll silverUsed = querySilver(rootPST[s], rootPST[t], rootPST[w], remY, 1, K);
ll goldSpent = totalCnt - silverUsed;
if(goldSpent > X) cout << -1 << "\n";
else cout << (X - goldSpent) << "\n";
}
return 0;
}
