#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define pb push_back
#define eb emplace_back
#define rep(x,y,z) for (int x=y;x<z;x++)
//bld pseg, range sum, point add, bs on four trees
const int mn=2e6;//1e5*4 + 1e5*17
vector<int> dis;
int sum[mn], num[mn], ll[mn], rr[mn];
int idx=0, rid=0;
#define m ((l+r)>>1)
int bld(int l, int r){
int id=idx++;
if (l==r){
sum[id]=0;
num[id]=0;
return id;
}
ll[id]=bld(l,m);
rr[id]=bld(m+1,r);
sum[id]=0;
num[id]=0;
return id;
}
int upd(int od, int l, int r, vector<int> pos){
if (pos.size()==0) return od;
int id=idx++;
if (l==r){
sum[id]=sum[od]+dis[l]*pos.size();
num[id]=num[od]+pos.size();
return id;
}
int cl=0;
for (int &i:pos) if (i<=m) cl++;
vector<int> lpos(cl),rpos(pos.size()-cl);
int cr=0; cl=0;
for (int &i:pos) if (i<=m) lpos[cl++]=i; else rpos[cr++]=i;
ll[id]=upd(ll[od],l,m,lpos);
rr[id]=upd(rr[od],m+1,r,rpos);
sum[id]=sum[ll[id]]+sum[rr[id]];
num[id]=num[ll[id]]+num[rr[id]];
return id;
}
int bs(int od, int id1, int id2, int rem, int cn, int l, int r){
int nn=num[id1]+num[id2]-num[od]*2;
if (l==r) return cn+min(rem/dis[l],nn);
int vl=sum[ll[id2]]+sum[ll[id2]]-sum[ll[od]]*2;
int nl=num[ll[id2]]+num[ll[id2]]-num[ll[od]]*2;
if (rem>=vl) return bs(rr[od],rr[id1],rr[id2],rem-vl,cn+nl,m+1,r);
return bs(ll[od],ll[id1],ll[id2],rem,cn,l,m);
}
#undef m
signed main(){
cin.tie(nullptr)->ios::sync_with_stdio(0);
int n,m,q;
cin>>n>>m>>q;
vector<vector<int>> adj(n);
vector<pii> edg(n-1);
rep(i,0,n-1){
int ca,cb;
cin>>ca>>cb;
ca--; cb--;
adj[ca].pb(cb);
adj[cb].pb(ca);
edg[i]={ca,cb};
}
vector<int> dep(n), lf(n), ff(n);
function<void(int,int)> cal=[&](int u, int f){
ff[u]=f;
int p=lf[ff[u]], q=lf[p];
if (dep[ff[u]]-dep[p]==dep[p]-dep[q]&&u!=f) lf[u]=q;
else lf[u]=ff[u];
for (int v:adj[u]){
if (v==f) continue;
dep[v]=dep[u]+1;
cal(v,u);
}
};
dep[0]=0;
cal(0,0);
dis.resize(m);
vector<vector<int>> add(n);
rep(i,0,m){
int x,v;
cin>>x>>v;
x--;
int ca,cb;
tie(ca,cb)=edg[x];
if (dep[ca]<dep[cb]) swap(ca,cb);
add[ca].pb(v);
dis[i]=v;
}
sort(all(dis));
dis.resize(unique(all(dis))-dis.begin());
rep(i,0,n){
for (int &j:add[i]){
j=lower_bound(all(dis),j)-dis.begin();
}
}
int k=dis.size();
vector<int> frt(n);
vector<int> rt(n);
vector<int> cnt(n);
frt[0]=bld(0,k-1);
function<void(int,int)> dfs=[&](int u, int f){
cnt[u]=cnt[f]+add[u].size();
rt[u]=upd(frt[u],0,k-1,add[u]);
for (int v:adj[u]){
if (v==f) continue;
frt[v]=rt[u];
dfs(v,u);
}
};
dfs(0,0);
while (q--){
int s,t,x,y;
cin>>s>>t>>x>>y;
s--; t--;
int ls=s, lt=t;
while (dep[ls]>dep[lt]){
if (dep[lf[ls]]>=dep[lt]) ls=lf[ls];
else ls=ff[ls];
}
while (dep[lt]>dep[ls]){
if (dep[lf[lt]]>=dep[ls]) lt=lf[lt];
else lt=ff[lt];
}
while (ls!=lt){
if (lf[ls]!=lf[lt]) ls=lf[ls],lt=lf[lt];
else ls=ff[ls], lt=ff[lt];
}
int lca=ls;
//int bs(int od, int id1, int id2, int rem, int cn, int l, int r){
int res=bs(rt[lca],rt[s],rt[t],y,0,0,k-1);
int tot=cnt[s]+cnt[t]-cnt[lca]*2;
// cout<<s+1<<' '<<t+1<<' '<<lca+1<<'\n';
// cout<<tot<<' '<<res<<'\n';
if ((tot-res)<=x) cout<<x-(tot-res)<<'\n';
else cout<<"-1\n";
}
return 0;
}
