#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,popcnt,sse4")
#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tlll tuple<ll,ll,ll>
const int mxn = 1e5+10;
vector<int> tree[mxn];
int par[mxn],link_top[mxn],sz[mxn],bs[mxn],idx[mxn],dep[mxn],cnt;
vector<ll> roads[mxn];
int N,M,Q;
vector<ll> all;
pii edges[mxn];
struct SEG{
#define ls now*2+1
#define rs now*2+2
#define mid ((l+r)>>1)
vector<pll> seg[mxn*4];
void build(int now,int l,int r){
if(l == r){
for(auto &i:roads[l])seg[now].push_back(pll(i,0));
}
else{
build(ls,l,mid);
build(rs,mid+1,r);
for(int i = 1;i<seg[ls].size();i++)seg[now].push_back(pll(seg[ls][i].fs,0));
for(int i = 1;i<seg[rs].size();i++)seg[now].push_back(pll(seg[rs][i].fs,0));
}
seg[now].push_back(pll(0,0));
sort(seg[now].begin(),seg[now].end());
for(int i = 1;i<seg[now].size();i++)seg[now][i].sc = seg[now][i-1].sc+seg[now][i].fs;
return;
}
vector<int> getrange(int now,int l,int r,int s,int e){
if(l>=s&&e>=r){
return {now};
}
if(mid>=e)return getrange(ls,l,mid,s,e);
else if(mid<s)return getrange(rs,mid+1,r,s,e);
else{
auto tl = getrange(ls,l,mid,s,e);
auto tr = getrange(rs,mid+1,r,s,e);
if(tl.size()>tr.size())for(auto &i:tr)tl.push_back(i);
else for(auto &i:tl)tr.push_back(i);
return (tl.size()>tr.size()?tl:tr);
}
}
#undef ls
#undef rs
#undef mid
};
void dfs1(int now){
sz[now] = 1;
for(auto nxt:tree[now]){
if(nxt == par[now])continue;
par[nxt] = now;
dep[nxt] = dep[now]+1;
dfs1(nxt);
sz[now] += sz[nxt];
if(!bs[now]||sz[bs[now]]<sz[nxt])bs[now] = nxt;
}
return;
}
void dfs2(int now,int top){
link_top[now] = top;
idx[now] = ++cnt;
if(bs[now])dfs2(bs[now],top);
for(auto nxt:tree[now]){
if(nxt == par[now]||nxt == bs[now])continue;
dfs2(nxt,nxt);
}
return;
}
SEG seg;
vector<int> LCA(int a,int b){
vector<int> re;
int ta = link_top[a],tb = link_top[b];
while(ta != tb){
if(dep[ta]<dep[tb]){
swap(a,b);
swap(ta,tb);
}
auto tv = seg.getrange(0,1,N,idx[ta],idx[a]);
for(auto &i:tv)re.push_back(i);
a = par[ta];
ta = link_top[a];
}
if(dep[a]>dep[b])swap(a,b);
if(a != b){
auto tv = seg.getrange(0,1,N,idx[a]+1,idx[b]);
for(auto &i:tv)re.push_back(i);
}
return re;
}
pll getall(vector<int>& ids,ll lim){
pll re = pll(0,0);
for(auto &i:ids){
auto p = lower_bound(seg.seg[i].begin(),seg.seg[i].end(),pll(lim+1,-1))-seg.seg[i].begin();
assert(p);
re.fs += seg.seg[i][p-1].sc;
re.sc += seg.seg[i].size()-p;
}
return re;
}
void solve(int s,int t,ll gold,ll silv){
vector<int> ids = LCA(s,t);
int l = 0,r = all.size()-1;
while(l != r){
int mid = (l+r+1)>>1;
if(getall(ids,all[mid]).fs>silv)r = mid-1;
else l = mid;
}
ll ans = -1;
//cout<<all[l]<<":"<<getall(ids,all[l]).fs<<','<<getall(ids,all[l]).sc<<"\n";
if(l == all.size()-1)ans = max(ans,gold-getall(ids,all[l]).sc);
else{
pll ta = getall(ids,all[l]);
pll tb = getall(ids,all[l+1]);
silv -= ta.fs;
//cout<<all[l]<<' '<<all[l+1]<<','<<ta.fs<<" "<<ta.sc<<','<<tb.fs<<' '<<tb.sc<<'\n';
gold = max(-1ll,gold-(ta.sc-min(silv/all[l+1],ta.sc-tb.sc)));
ans = gold;
}
cout<<ans<<'\n';
return;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>N>>M>>Q;
for(int i = 1;i<N;i++){
int a,b;
cin>>a>>b;
edges[i] = pii(a,b);
tree[a].push_back(b);
tree[b].push_back(a);
}
par[1] = 1;
dfs1(1);
dfs2(1,1);
assert(cnt == N);
for(int i = 0;i<M;i++){
ll p,val;
cin>>p>>val;
all.push_back(val);
auto &[a,b] = edges[p];
if(dep[a]>dep[b])swap(a,b);
assert(dep[b]-dep[a] == 1);
roads[idx[b]].push_back(val);
}
all.push_back(0);
sort(all.begin(),all.end());all.resize(unique(all.begin(),all.end())-all.begin());
seg.build(0,1,N);
while(Q--){
ll s,t,gold,silv;
cin>>s>>t>>gold>>silv;
solve(s,t,gold,silv);
}
}
