#include<bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define int long long
#define vi vector<int>
#define vvi vector<vector<int>>
#define pii pair<int, int>
#define vpii vector<pair<int, int>>
#define vc vector<char>
#define vb vector<bool>
#define mii map<int,int>
#define f0r(i,n) for(int i=0;i<n;i++)
#define FOR(i,k,n) for(int i=k;i<n;i++)
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define in(a) int a; cin>>a
#define in2(a,b) int a,b; cin>>a>>b
#define in3(a,b,c) int a,b,c; cin>>a>>b>>c
#define in4(a,b,c,d) int a,b,c,d; cin>>a>>b>>c>>d
#define vin(v,n); vi v(n); f0r(i,n){cin>>v[i];}
#define out(a) cout<<a<<'\n'
#define out2(a,b) cout<<a<<' '<<b<<'\n'
#define out3(a,b,c) cout<<a<<' '<<b<<' '<<c<<'\n'
#define out4(a,b,c,d) cout<<a<<' '<<b<<' '<<c<<' '<<d<<'\n'
#define vout(v) for(auto u : v){cout<<u<<' ';} cout<<'\n'
#define dout(a) cout<<a<<' '<<#a<<'\n'
#define dout2(a,b) cout<<a<<' '<<#a<<' '<<b<<' '<<#b<<'\n'
#define yn(x); if(x){cout<<"YES"<<'\n';}else{cout<<"NO"<<'\n';}
const int leg = 1e9 + 7;
const int mod = 998244353;
using namespace std;
const int mxn = 1e5 + 5;
vi adj[mxn];
vi dep(mxn), par(mxn), tin(mxn), tout(mxn);
int timer = 0;
void dfs(int node, int from){
par[node] = from;
tin[node] = timer++;
for(auto u : adj[node]){
if(u != from){
dep[u] = dep[node] + 1;
dfs(u, node);
}
}
tout[node] = timer++;
}
vi s(mxn);
vi cnt(mxn);
void dfs2(int node, int from){
for(auto u : adj[node]){
if(u != from){
s[u] = s[node] + cnt[u];
dfs2(u, node);
}
}
}
vvi jmp(mxn, vi(17));
int lca(int a, int b){
if(dep[a] < dep[b])swap(a,b);
int diff = dep[a] - dep[b];
f0r(i, 17){
if(diff & (1<<i)){
a = jmp[a][i];
}
}
if(a == b)return a;
for(int i = 16; i>=0; i--){
if(jmp[a][i] != jmp[b][i]){
a = jmp[a][i];
b = jmp[b][i];
}
}
return par[a];
}
struct BIT{
int n;
vi bit;
BIT(int n) : n(n), bit(n+1,0){}
void add(int k, int x){
k++;
while(k <= n){
bit[k] += x;
k += k & -k;
}
}
int sum(int x){
int ans = 0;
while(x >= 1){
ans += bit[x];
x -= x & -x;
}
return ans;
}
};
signed main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
//ifstream cin(".in");
//ofstream cout(".out");
in3(n,m,q);
vpii edges;
f0r(i,n-1){
in2(a,b);
a--; b--;
adj[a].pb(b);
adj[b].pb(a);
edges.pb(mp(a,b));
}
dfs(0,-1);
vi edgetonode(n-1);
f0r(i,n-1){
edgetonode[i] = (dep[edges[i].first] > dep[edges[i].second] ? edges[i].first : edges[i].second);
}
f0r(i,n){
jmp[i][0] = par[i];
}
FOR(i,1,17){
f0r(j,n){
if(jmp[j][i-1] == -1)jmp[j][i] = -1;
else jmp[j][i] = jmp[jmp[j][i-1]][i-1];
}
}
// vout(dep);
vpii gates;
f0r(i,m){
in2(p,c);
p--;
p = edgetonode[p];
gates.pb(mp(c,p));
}
sort(all(gates));
f0r(i,m)swap(gates[i].first,gates[i].second);
// f0r(i,m)out2(gates[i].first, gates[i].second);
dfs2(0,-1);
// out(lca(2,8));
// f0r(i,n)cout<<cnt[i]<<' ';
// cout<<'\n';
vi S(q), T(q), X(q), Y(q), L(q);
f0r(i,q){
in4(a,b,c,d);
a--; b--;
S[i] = a;
T[i] = b;
X[i] = c;
Y[i] = d;
L[i] = lca(a,b);
}
vi lef(q,-1), rig(q, m+1), ans(q);
while(1){
bool ok = 1;
vector<vi>id(m+1);
f0r(i,q){
if(rig[i] - lef[i] > 1){
ok = 0;
id[(rig[i] + lef[i]) / 2].pb(i);
}
}
if(ok)break;
BIT b1(n*2-2);
BIT b2(n*2-2);
f0r(i,m){
b1.add(tin[gates[i].first], 1);
b1.add(tout[gates[i].first], -1);
}
f0r(i, m+1){
for(auto u : id[i]){
int cur = b2.sum(tin[S[u]] + 1) + b2.sum(tin[T[u]] + 1) - 2 * b2.sum(tin[L[u]] + 1);
if(cur <= Y[u]){
ans[u] = b1.sum(tin[S[u]] + 1) + b1.sum(tin[T[u]] + 1) - 2 * b1.sum(tin[L[u]] + 1);
lef[u] = i;
}
else rig[u] = i;
}
if(i != m){
b1.add(tin[gates[i].first], -1);
b1.add(tout[gates[i].first], 1);
b2.add(tin[gates[i].first], gates[i].second);
b2.add(tout[gates[i].first], -gates[i].second);
}
}
}
// vout(lef);
// vout(rig);
// vout(ans);
f0r(i,q)cout<<max(X[i] - ans[i], -1LL)<<'\n';
}
