#include <bits/stdc++.h>
using namespace std;
struct node{
long long val,cnt;
node *l, *r;
node(long long V, long long C){
val=V;
cnt=C;
l=r=NULL;
}
node(node* le, node* ri){
l=le;
r=ri;
val=l->val+r->val;
cnt=l->cnt+r->cnt;
}
};
void prop(node* nd){
if(nd->l==NULL){
nd->r=new node(0LL,0LL);
nd->l=new node(0LL,0LL);
}
}
node* update(node* lol, int s, int e, int x){
if(s==e) return new node(lol->val+s,lol->cnt+1);
int mid=(s+e)/2;
prop(lol);
if(x<=mid) return new node(update(lol->l,s,mid,x),lol->r);
else return new node(lol->l,update(lol->r,mid+1,e,x));
}
long long bsta(node* base, node* base2, node* one, node* two, int s, int e, long long V){
long long tcnt=one->cnt+two->cnt-base->cnt-base2->cnt;
if(s==e){
return min(tcnt,V/(long long)s);
}
int mid=(s+e)/2;
prop(base); prop(base2); prop(one); prop(two);
long long ltcnt=one->l->cnt+two->l->cnt-base->l->cnt-base2->l->cnt;
long long ltval=one->l->val+two->l->val-base->l->val-base2->l->val;
if(ltval>V) return bsta(base->l,base2->l,one->l,two->l,s,mid,V);
else return ltcnt+bsta(base->r,base2->r,one->r,two->r,mid+1,e,V-ltval);
}
node* nodes[200005];
vector<int> adj[200005];
long long cost[200005];
int par[200005];
void dfs(int x, int p){
nodes[x]=update(nodes[p],0,1000000005,cost[x]);
for(int i:adj[x]){
if(i==p) continue;
par[i]=x;
dfs(i,x);
}
}
const int MAXN = 200050;
const int LOGN = 20;
int p[LOGN+1][MAXN], h[MAXN]; //h: number of edges from root
bitset<MAXN> visited;
void dfss(int x) {
if (visited[x]) return;
visited[x] = 1LL;
for (int k = 0LL; k < LOGN; ++k) {
if (p[k][x] == -1LL) break;
p[k+1LL][x] = p[k][p[k][x]];
}
for (int it:adj[x]) {
if (visited[it]) continue;
p[0][it] = x;
h[it] = h[x] + 1LL;
dfss(it);
}
}
/* Query */
int lca(int a, int b) { //h[a] < h[b]
if (h[a] > h[b]) swap(a, b);
/* advance b by h[b] - h[a] parents */
for (int k = 0, d = h[b] - h[a]; k < LOGN; ++k) {
if (d & (1<<k)) b = p[k][b];
}
if (a == b) return a;
assert(h[a] == h[b]); //same height
/* to be continued */
for (int k = LOGN-1; k >= 0; --k) {
if (p[k][a] != p[k][b])
a = p[k][a], b = p[k][b];
}
assert(p[0][a] == p[0][b]); //same immediate parent
return p[0][a];
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
memset(p,-1,sizeof(p));
int n,m,q;
cin >> n >> m >> q;
vector<pair<int,int> > edges;
for(int i=0; i<n-1; i++){
int a,b;
cin >> a >> b;
edges.push_back({a,b});
}
int cnt=n+1LL;
for(int i=0; i<m; i++){
int a;
long long b;
cin >> a >> b;
cost[cnt]=b;
edges.push_back({cnt,edges[a-1LL].second});
edges[a-1LL].second=cnt;
cnt++;
}
for(auto i:edges){
adj[i.first].push_back(i.second);
adj[i.second].push_back(i.first);
}
nodes[0]=new node(0LL,0LL);
dfs(1LL,0LL);
dfss(1LL);
for(int i=0; i<q; i++){
int a,b;
long long c,d;
cin >> a >> b >> c >> d;
int o=lca(a,b);
int cry=par[o];
long long yes=bsta(nodes[o],nodes[cry],nodes[a],nodes[b],0,1000000005,d);
long long ret=c-(h[a]+h[b]-2*h[o]+1-yes);
if(ret<0) cout << -1 << '\n';
else cout << ret << '\n';
}
}
/*5 4 3
1 2
1 3
2 4
2 5
2 9
2 4
3 5
4 7
3 4 2 11
5 3 4 5
2 3 1 1*/
