#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define se second
#define fi first
#define ll long long
#define ii pair<ll, ll>
const long mxN = 1e5 + 7;
int n, m, q, par[mxN][25], h[mxN], cnt[mxN], l[mxN], r[mxN], mid[mxN], u[mxN], v[mxN], vt[mxN], gold[mxN], ans[mxN];
ll sum[mxN], silver[mxN];
ii Nen[mxN], tree[mxN * 4];
vector<ii> querry[mxN];
vector<int> w[mxN], sta[mxN];
void Build(int j)
{
for (int i = 1; i < 20; i++)
par[j][i] = par[par[j][i - 1]][i - 1];
for (int i : w[j])
{
if (i == par[j][0])
continue;
h[i] = h[j] + 1;
par[i][0] = j;
Build(i);
}
}
int LCA(int u, int v)
{
if (h[u] < h[v])
swap(u, v);
for (int i = 19; i >= 0; i--)
{
if (h[par[u][i]] >= h[v])
u = par[u][i];
}
if (u == v)
return u;
for (int i = 19; i >= 0; i--)
{
if (par[u][i] != par[v][i])
{
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
// Cong 2 pair
ii Plus(ii u, ii v)
{
u.fi += v.fi;
u.se += v.se;
return u;
}
void Upd(int vt, bool tt, int j = 1, int l = 1, int r = m)
{
if (l > vt || vt > r)
return;
if (l == r)
{
//fi la so luong
//se la chi phi
tree[j].fi = tt;
tree[j].se = tt * Nen[l].fi;
return;
}
int mid = (l + r) / 2;
Upd(vt, tt, j * 2, l, mid);
Upd(vt, tt, j * 2 + 1, mid + 1, r);
tree[j] = Plus(tree[j * 2], tree[j * 2 + 1]);
}
// lay tong nhung gia tri nho nhat be hon mid
ii Get(int vt, int j = 1, int l = 1, int r = m)
{
if (vt < l)
return {0, 0};
if (r <= vt)
return tree[j];
int mid = (l + r) / 2;
return Plus(Get(vt, j * 2, l, mid), Get(vt, j * 2 + 1, mid + 1, r));
}
void DFS(int j)
{
for (int i : sta[j])
Upd(vt[i], 1);
for (ii i : querry[j])
{
if (l[i.fi] > r[i.fi])
continue;
ii tmp = Get(mid[i.fi]);
sum[i.fi] += tmp.se * i.se;
cnt[i.fi] += (tree[1].fi - tmp.fi) * i.se;
}
for (int i : w[j])
{
if (i == par[j][0])
continue;
DFS(i);
}
for (int i : sta[j])
Upd(vt[i], 0);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> n >> m >> q;
for (int i = 1; i < n; i++)
{
cin >> u[i] >> v[i];
w[u[i]].push_back(v[i]);
w[v[i]].push_back(u[i]);
}
Build(1);
for (int i = 1; i <= m; i++)
{
int id, cost;
cin >> id >> cost;
if (u[id] != par[v[id]][0])
swap(u[id], v[id]);
sta[v[id]].push_back(i);
Nen[i] = {cost, i};
}
sort(Nen + 1, Nen + m + 1);
for (int i = 1; i <= m; i++)
vt[Nen[i].se] = i;
for (int i = 1; i <= q; i++)
{
int u, v;
cin >> u >> v >> gold[i] >> silver[i];
int root = LCA(u, v);
l[i] = 0;
r[i] = m;
ans[i] = -1;
querry[u].push_back({i, 1});
querry[v].push_back({i, 1});
querry[root].push_back({i, -2});
}
while (1)
{
bool tt = 0;
for (int i = 1; i <= q; i++)
{
sum[i] = 0;
cnt[i] = 0;
tt |= (l[i] <= r[i]);
mid[i] = (l[i] + r[i]) / 2;
}
if (!tt)
break;
DFS(1);
for (int i = 1; i <= q; i++)
{
if (l[i] > r[i])
continue;
if (sum[i] > silver[i])
r[i] = mid[i] - 1;
else
{
l[i] = mid[i] + 1;
ans[i] = gold[i] - cnt[i];
}
}
}
for (int i = 1; i <= q; i++)
cout << max(-1, ans[i]) << '\n';
}
/*
8 7 1
1 2
2 3
3 4
4 5
5 6
6 7
7 8
4 4
3 7
2 10
5 2
4 1
4 4
5 6
7 1 5 55
*/
