#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define thuhien ""
#define re exit(0);
const int maxn = 100009;
const int LOG = 17;
ll fen[maxn];
int fencnt[maxn];
void update(int pos,int val) {
for (;pos <= 100003;pos += (pos & -pos)) {
fen[pos] += val;
fencnt[pos] += val < 0 ? -1 : 1;
}
}
void update(int l,int r,int val) {
update(l,val);
update(r + 1,-val);
}
ll get(int pos) {
ll ret = 0;
for (;pos;pos -= (pos & -pos)) ret += fen[pos];
return ret;
}
int getnum(int pos) {
int ret = 0;
for (;pos;pos -= (pos & -pos)) ret += fencnt[pos];
return ret;
}
int n,m,q;
vector <int> adj[maxn];
pair <int,int> edge[maxn];
pair <int,int> checkpoints[maxn];
int tin[maxn],tout[maxn],timedfs;
int h[maxn],up[maxn][LOG + 1],depth[maxn];
void predfs(int node,int par) {
tin[node] = ++timedfs;
for (int x : adj[node]) if (x != par) {
h[x] = h[node] + 1;
up[x][0] = node;
for (int i = 1;i <= LOG;i++) {
up[x][i] = up[up[x][i - 1]][i - 1];
}
predfs(x,node);
}
tout[node] = timedfs;
}
void dfs(int node,int par) {
for (int x : adj[node]) if (x != par) {
depth[x] += depth[node];
dfs(x,node);
}
}
int lca(int u,int v) {
if (h[u] < h[v]) swap(u,v);
int diff = h[u] - h[v];
for (int i = LOG;i >= 0;i--) if (diff >> i & 1) u = up[u][i];
if (u == v) return u;
for (int i = LOG;i >= 0;i--) if (up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
return up[u][0];
}
struct ped {
int u,v,lca,gold;
ll silver;
int index;
};
int answer[maxn];
int pt = 0;
void move(int mid) {
while (pt < mid) {
pt++;
int u = checkpoints[pt].first;
update(tin[u],tout[u],checkpoints[pt].second);
}
while (pt > mid) {
int u = checkpoints[pt].first;
update(tin[u],tout[u],-checkpoints[pt].second);
pt--;
}
}
void binsearch(int l,int r,vector <ped> all) {
if (l > r) {
move(r);
for (ped x : all) {
int temp = getnum(tin[x.u]) + getnum(tin[x.v]) - 2*getnum(tin[x.lca]);
int temp2 = depth[x.u] + depth[x.v] - 2*depth[x.lca];
answer[x.index] = max(-1,x.gold - (temp2 - temp));
// answer[x.index] = r;
}
return;
}
if (all.empty()) return;
int mid = (l + r) >> 1;
move(mid);
vector <ped> left,right;
for (ped x : all) {
ll DICK = get(tin[x.u]) + get(tin[x.v]) - 2*get(tin[x.lca]);
// if (x.u == 5 && x.v == 3) cout << DICK << " " << l << " " << r << " " << x.silver << '\n';
if (DICK <= x.silver) right.push_back(x); //l = mid + 1;
else left.push_back(x); //r = mid - 1;
}
binsearch(l,mid - 1,left);
left.clear();
binsearch(mid + 1,r,right);
right.clear();
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(nullptr);
if (fopen(thuhien".inp","r")) {
freopen(thuhien".inp","r",stdin);
freopen(thuhien".out","w",stdout);
}
cin >> n >> m >> q;
for (int i = 1;i < n;i++) {
int u,v;cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
edge[i] = {u,v};
}
predfs(1,-1);
for (int i = 1;i <= m;i++) {
int a;
cin >> a >> checkpoints[i].second;
int u = edge[a].first,v = edge[a].second;
if (h[u] < h[v]) swap(u,v);
checkpoints[i].first = u;
depth[u] ++;
}
sort(checkpoints + 1,checkpoints + 1 + m,[] (pair <int,int> a,pair <int,int> b) {
return a.second < b.second;
});
dfs(1,-1);
vector <ped> all;
for (int i = 1;i <= q;i++) {
int u,v,gold;ll silver;cin >> u >> v >> gold >> silver;
all.push_back({u,v,lca(u,v),gold,silver,i});
}
binsearch(1,m,all);
for (int i = 1;i <= q;i++) cout << answer[i] << '\n';
}
