#include<bits/stdc++.h>
#define ll long long
#define pll pair<ll, ll>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define ld long double
using namespace std;
struct BIT
{
ll n;
vector <ll> bit;
BIT (ll n): n(n)
{
bit.assign(n+1, 0);
}
void update(ll l, ll r, ll val)
{
for (; l<=n; l+=l&(-l))
bit[l]+=val;
for (++r; r<=n; r+=r&(-r))
bit[r]-=val;
}
ll query(ll i)
{
ll ans=0;
for (; i; i-=i&(-i))
ans+=bit[i];
return ans;
}
};
const ll maxn=100005;
vector <pll> euler;
pll edge[maxn], sp[20][maxn];
vector <ll> A[maxn], C[maxn], Q[maxn];
ll Time, tin[maxn], tout[maxn], lca[maxn], pa[maxn], dis[maxn];
ll p[maxn], c[maxn], s[maxn], t[maxn], x[maxn], y[maxn], l[maxn], r[maxn], ans[maxn];
void dfs(ll u)
{
tin[u]=++Time;
lca[u]=euler.size()+1;
euler.pb({lca[u], u});
for (ll v:A[u])
if (v!=pa[u])
{
pa[v]=u, dfs(v);
euler.pb({lca[u], u});
}
tout[u]=Time;
}
void getdis(ll u)
{
for (ll v:A[u])
if (v!=pa[u])
dis[v]+=dis[u], getdis(v);
}
void init_sparse()
{
ll n=euler.size();
for (ll i=0; i<n; i++)
sp[0][i+1]=euler[i];
for (ll i=1; i<20; i++)
for (ll j=1; j+(1<<i)<=n+1; j++)
sp[i][j]=min(sp[i-1][j], sp[i-1][j+(1<<i-1)]);
}
ll LCA(ll u, ll v)
{
ll l=lca[u], r=lca[v];
if (l>r) swap(l, r);
ll j=__lg(r-l+1);
return min(sp[j][l], sp[j][r-(1<<j)+1]).se;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll n, m, q; cin >> n >> m >> q;
for (ll i=1; i<n; i++)
{
ll u, v; cin >> u >> v;
A[u].pb(v); A[v].pb(u);
edge[i]={u, v};
}
vector <pll> numc;
dfs(1); init_sparse();
for (ll i=1; i<n; i++)
if (edge[i].se==pa[edge[i].fi])
swap(edge[i].fi, edge[i].se);
for (ll i=1; i<=m; i++)
{
cin >> p[i] >> c[i];
numc.pb({c[i], edge[p[i]].se});
dis[edge[p[i]].se]++;
}
sort(numc.begin(), numc.end());
getdis(1);
for (ll i=1; i<=q; i++)
{
cin >> s[i] >> t[i] >> x[i] >> y[i];
l[i]=0, r[i]=m, ans[i]=-1;
}
for (ll z=0; z<20; z++)
{
for (ll i=1; i<=q; i++)
Q[(l[i]+r[i]+1)/2].pb(i);
BIT A(n), B(n);
for (ll i=0; i<=m; i++)
{
if (i)
{
ll P=numc[i-1].se;
A.update(tin[P], tout[P], numc[i-1].fi);
B.update(tin[P], tout[P], 1);
}
for (ll idx:Q[i])
{
ll u=s[idx], v=t[idx], X=x[idx], Y=y[idx], lca=LCA(u, v);
ll sum=A.query(tin[u])+A.query(tin[v])-A.query(tin[lca])*2;
ll cnt=B.query(tin[u])+B.query(tin[v])-B.query(tin[lca])*2;
ll cnt2=dis[u]+dis[v]-dis[lca]*2;
if (sum<=Y)
{
if (cnt2-cnt<=X) ans[idx]=max(ans[idx], X-(cnt2-cnt));
l[idx]=i;
}
else r[idx]=i-1;
}
Q[i].clear();
}
}
for (ll i=1; i<=q; i++)
cout << ans[i] << "\n";
}
