# include <iostream>
# include <vector>
# include <algorithm>
//# define endl "\n"
using namespace std;
const int MAX=1e5+11,LOG=20;
int n,m,q;
pair<int,int> edges[MAX];
vector<int> adj[MAX];
int h[MAX];
int st[MAX][LOG];
void dfs_init(int curr, int par)
{
for(int nxt: adj[curr])
{
if(nxt==par) continue;
h[nxt]=h[curr]+1;
st[nxt][0]=curr;
dfs_init(nxt,curr);
}
}
int get_lca(int u, int v)
{
if(h[u]<h[v]) swap(u,v);
for(int j=LOG-1;j>=0;j--)
{
if(h[u]-(1<<j)>=h[v]) u=st[u][j];
}
if(u==v) return u;
for(int j=LOG-1;j>=0;j--)
{
if(h[u]-(1<<j)>=0 and st[u][j]!=st[v][j])
{
u=st[u][j];
v=st[v][j];
}
}
return st[u][0];
}
void lca_precalc()
{
dfs_init(1,0);
for(int j=1;j<LOG;j++)
{
for(int i=1;i<=n;i++)
{
if(h[i]-(1<<j)<0) continue;
st[i][j]=st[st[i][j-1]][j-1];
}
}
}
pair<int,int> cp[MAX];
int real_value[MAX];
vector<int> cpts[MAX];
int cnt_cpts[MAX];
struct node
{
long long cost,cnt;
node(){cost=0;cnt=0;}
node(long long _cost, long long _cnt) {cost=_cost;cnt=_cnt;}
node friend operator + (node A, node B)
{
return {A.cost+B.cost,A.cnt+B.cnt};
}
};
const int Tsz=MAX*LOG;
int ct,M;
int roots[MAX];
node tree[Tsz];
int lv[Tsz];
int rv[Tsz];
int update(int pos, int d, int v, int l=1, int r=M)
{
if(l==r)
{
ct++;
tree[ct]=tree[v];
tree[ct].cost+=d;
tree[ct].cnt++;
return ct;
}
int mid=(l+r)/2;
if(pos<=mid)
{
ct++;
int v2=ct;
lv[v2]=update(pos,d,lv[v],l,mid);
rv[v2]=rv[v];
tree[v2]=tree[lv[v2]]+tree[rv[v2]];
return v2;
}
else
{
ct++;
int v2=ct;
lv[v2]=lv[v];
rv[v2]=update(pos,d,rv[v],mid+1,r);
tree[v2]=tree[lv[v2]]+tree[rv[v2]];
return v2;
}
}
void dfs(int curr, int par)
{
cnt_cpts[curr]=cpts[curr].size()+cnt_cpts[par];
roots[curr]=roots[par];
for(int x: cpts[curr]) roots[curr]=update(x,real_value[x],roots[curr]);
for(int nxt: adj[curr])
{
if(nxt==par) continue;
dfs(nxt,curr);
}
}
long long query(long long k, int u, int v, int lca, int l=1, int r=M)
{
//cout<<l<<" "<<r<<" "<<real_value[l]<<endl;
if(l==r)
{
long long cnt=tree[u].cnt+tree[v].cnt-tree[lca].cnt*2;
return min(k/real_value[l],cnt);
}
long long cost=tree[u].cost+tree[v].cost-tree[lca].cost*2;
long long cnt=tree[u].cnt+tree[v].cnt-tree[lca].cnt*2;
int mid=(l+r)/2;
if(cost>k) return query(k,lv[u],lv[v],lv[lca],l,mid);
else return cnt+query(k-cost,rv[u],rv[v],rv[lca],mid+1,r);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>m>>q;
for(int i=1;i<n;i++)
{
int u,v;
cin>>u>>v;
edges[i]={u,v};
adj[u].push_back(v);
adj[v].push_back(u);
}
lca_precalc();
vector<pair<int,int>> temp;
for(int i=1;i<=m;i++)
{
cin>>cp[i].first>>cp[i].second;
temp.push_back({cp[i].second,i});
}
sort(temp.begin(),temp.end());
int last=-1,ctt=0;
for(pair<int,int> pa: temp)
{
if(pa.first!=last)
{
ctt++;
real_value[ctt]=pa.first;
last=pa.first;
}
cp[pa.second].second=ctt;
}
M=ctt;
for(int i=1;i<=m;i++)
{
int u=edges[cp[i].first].first;
int v=edges[cp[i].first].second;
if(h[u]>h[v]) swap(u,v);
cpts[v].push_back(cp[i].second);
}
roots[0]=0;
dfs(1,0);
while(q--)
{
int u,v,lca;
long long x,y;
cin>>u>>v>>x>>y;
lca=get_lca(u,v);
//cout<<"->"<<lca<<endl;
long long ans=(cnt_cpts[u]+cnt_cpts[v]-cnt_cpts[lca]*2)-query(y,roots[u],roots[v],roots[lca]);
x-=max(0LL,ans);
if(x>=0) cout<<x<<"\n";
else cout<<-1<<"\n";
}
return 0;
}
