#include<bits/stdc++.h>
using namespace std;
#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define rep(i,a) for(int i=0; i<(a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(),(a).end()
#define bit(s,i) (((s)>>(i))&1)
#define ii pair<int,int>
#define vi vector<int>
#define vii vector<ii>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
#define _ << " " <<
template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;}
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}
const int N=1e5+5;
const int LG=17;
int n,m,q;
vii adj[N];
int s[N],t[N],gol[N],lst[N]; ll sil[N];
struct checkPoint{
int idE, numSil;
bool operator < (const checkPoint &o) const {
return numSil < o.numSil;
}
} cp[N];
int up[N][LG+1],h[N],tin[N],tout[N],tim,idV[N];
void dfs(int u, int p=-1){
tin[u]=++tim;
for(auto [v,id]:adj[u]) if(v!=p){
up[v][0]=u;
foru(i,1,LG){
up[v][i]=up[up[v][i-1]][i-1];
}
h[v]=h[u]+1;
idV[id]=v;
dfs(v,u);
}
tout[u]=tim;
}
int lca(int u, int v){
if(h[u]<h[v]) swap(u,v);
int dd=h[u]-h[v];
foru(i,0,LG) if(bit(dd,i)) u=up[u][i];
if(u==v) return u;
ford(i,LG,0) if(up[u][i]!=up[v][i]) u=up[u][i], v=up[v][i];
return up[u][0];
}
int L[N],R[N],resG[N];
template<class T>
struct BIT{
T f[N];
void reset(){
memset(f,0,sizeof(f));
}
void upd(int id, T val){
for(; id<=n; id+=id&-id) f[id]+=val;
}
void upd(int l, int r, T val){
upd(l,val); upd(r+1,-val);
}
T get(int id){
T res=0;
for(; id>0; id-=id&-id) res+=f[id];
return res;
}
};
BIT<int> totG;
BIT<ll> totS;
vi que[N];
void solve(){
cin>>n>>m>>q;
foru(i,1,n-1){
int u,v; cin>>u>>v;
adj[u].eb(v,i); adj[v].eb(u,i);
}
foru(i,1,m) cin>>cp[i].idE>>cp[i].numSil;
foru(i,1,q) cin>>s[i]>>t[i]>>gol[i]>>sil[i];
dfs(1);
sort(cp+1, cp+1+m);
foru(i,1,q){
L[i]=0; R[i]=m; resG[i]=-1;
lst[i]=lca(s[i],t[i]);
}
while(true){
totG.reset();
totS.reset();
foru(i,0,m) que[i].clear();
bool chk=0;
foru(i,1,q){
if(L[i]<=R[i]){
int M=(L[i]+R[i])>>1;
que[M].eb(i);
chk=1;
}
}
if(!chk) break;
foru(i,1,m){
int v=idV[cp[i].idE];
totG.upd(tin[v],tout[v],1);
}
foru(i,0,m){
if(i>0){
int v=idV[cp[i].idE];
totG.upd(tin[v],tout[v],-1);
totS.upd(tin[v],tout[v],cp[i].numSil);
}
for(int j:que[i]){
ll tot=totS.get(tin[s[j]]) + totS.get(tin[t[j]]) - 2*totS.get(tin[lst[j]]);
int M=(L[j]+R[j])>>1;
if(tot<=sil[j]){
resG[j]=totG.get(tin[s[j]]) + totG.get(tin[t[j]]) - 2*totG.get(tin[lst[j]]);
L[j]=M+1;
} else{
R[j]=M-1;
}
}
}
}
foru(i,1,q){
if(resG[i]>gol[i]){
cout<<"-1\n";
} else{
cout<<gol[i]-resG[i]<<'\n';
}
}
}
int32_t main(){
#define task "test"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin.tie(0)->sync_with_stdio(0);
int tc=1; //cin>>tc;
foru(i,1,tc){
solve();
}
}
