#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace std;
//using namespace __gnu_pbds;
#define FOR(i, x, y) for(ll i=x; i<y; i++)
#define FORNEG(i, x, y) for(ll i=x; i>y; i--)
//#define ordered_set tree<ll, null_type,less_equal<ll>, rb_tree_tag,tree_order_statistics_node_update>
#define fast() ios_base::sync_with_stdio(false);cin.tie(NULL)
vector<ll> edges[100001];
ll toll[100001];
ll par[100001];
ll depth[100001];
ll pref[100001];
ll ancc[100001][20];
ll fixcost = 0;
vector<vector<ll>> stuff;
void dfs(ll a, ll p, ll d){
par[a] = p;
depth[a] = d;
for (auto&i : edges[a]){
if (i!=p) dfs(i, a, d+1);
}
}
void dfs2(ll a, ll p){
if (p!=-1) pref[a] = pref[p] + toll[a];
for (auto&i : edges[a]){
if (i!=p) dfs2(i, a);
}
}
ll anc(ll a, ll jump){
if (ancc[a][jump] != -1) return ancc[a][jump];
if (depth[a] - (1<<jump) <= 0) return 1;
if (jump == 0) return par[a];
ancc[a][jump] = anc(anc(a, jump-1), jump-1);
return ancc[a][jump];
}
ll lca(ll a, ll b){
if (depth[a] < depth[b]) swap(a,b);
FORNEG(i,19,-1) if (depth[anc(a, i)] >= depth[b]) a=anc(a,i);
if (a==b) return a;
FORNEG(i,19,-1) if (anc(a,i) != anc(b,i)) a = anc(a,i), b = anc(b, i);
return par[a];
}
int main(){
FOR(i,0,100001) toll[i] = 0, par[i] = -1, depth[i] = 0, pref[i] = 0;
FOR(i,0,100001) FOR(j,0,20) ancc[i][j] = -1;
ll n,m,q;
cin >> n >> m >> q;
FOR(i,0,n-1){
ll a,b;
cin >> a >> b;
stuff.push_back({a,b});
edges[a].push_back(b);
edges[b].push_back(a);
}
dfs(1, -1, 0);
FOR(i,0,m){
ll c,d;
cin >> c >> d;
ll a = stuff[c-1][0];
ll b = stuff[c-1][1];
if (par[b] == a) toll[b] += d;
else toll[a] += d;
fixcost = d;
}
dfs2(1, -1);
FOR(i,0,q){
ll a,b,c,d;
cin >> a >> b >> c >> d;
ll total = 0;
total += pref[a];
total += pref[b];
total -= 2*pref[lca(a,b)];
ll count = total/fixcost;
count -= (d/fixcost);
count = max(count, (ll) 0);
if (c-count < 0 ) cout << -1 << "\n";
else cout << c-count << "\n";
}
}
