#include <bits/stdc++.h>
#define N 100011
#define ll long long
using namespace std;
int n,m,q,fa[N][21],ndE[N],dep[N],rt[N],sz,U[N],V[N];vector<int> w[N];
vector<int> G[N];
int lca(int u,int v)
{
	if(dep[u]<dep[v])swap(u,v);for(int i=20;~i;--i)if(dep[u]-(1<<i)>=dep[v])u=fa[u][i];if(u==v)return u;
	for(int i=20;~i;--i)if(fa[u][i]^fa[v][i])u=fa[u][i],v=fa[v][i];return fa[u][0];
}
ll sum[N*50],dis[N];int lc[N*50],rc[N*50],cnt[N*50];
void pushup(int x){sum[x]=sum[lc[x]]+sum[rc[x]];cnt[x]=cnt[lc[x]]+cnt[rc[x]];}
void add(int k,ll v,int L,int R,int x,int &c)
{
	if(!c)c=++sz;if(L==R){sum[c]=sum[x]+v;cnt[c]=cnt[x]+1;return;}
	if(k<=L+R>>1)rc[c]=rc[x],add(k,v,L,L+R>>1,lc[x],lc[c]);else lc[c]=lc[x],add(k,v,(L+R>>1)+1,R,rc[x],rc[c]);pushup(c);
}
int bin(int r1,int r2,int r3,int r4,ll v,int L,int R)
{
	if(L==R)return L;
	if(sum[rc[r1]]+sum[rc[r2]]-sum[rc[r3]]-sum[rc[r4]]>v)return bin(rc[r1],rc[r2],rc[r3],rc[r4],v,(L+R>>1)+1,R);
	else return bin(lc[r1],lc[r2],lc[r3],lc[r4],v-(sum[rc[r1]]+sum[rc[r2]]-sum[rc[r3]]-sum[rc[r4]]),L,L+R>>1);
}
int query(int l,int r,int L,int R,int x)
{
	if(!x)return 0;if(l<=L&&R<=r)return cnt[x];int ans=0;
	if(l<=L+R>>1)ans+=query(l,r,L,L+R>>1,lc[x]);if(r>L+R>>1)ans+=query(l,r,(L+R>>1)+1,R,rc[x]);return ans;
}
void dfs(int u,int f)
{
	fa[u][0]=f;for(int i=1;i<=20;++i)fa[u][i]=fa[fa[u][i-1]][i-1];dep[u]=dep[f]+1;
	for(int v:G[u])if(v^f)dfs(v,u);
}
void dfs_(int u,int f)
{
	int lst=rt[f];
	for(int x:w[u])add(x,x,1,1e9,lst,rt[u]),lst=rt[u];dis[u]=dis[f];for(int x:w[u])dis[u]+=x;
	for(int v:G[u])if(v^f)dfs_(v,u);
}
int main()
{
	scanf("%d%d%d",&n,&m,&q);
	for(int i=1;i<n;++i){int u,v;scanf("%d%d",&u,&v);G[u].push_back(v);G[v].push_back(u);U[i]=u;V[i]=v;}
	dfs(1,0);
	for(int i=1;i<n;++i)if(dep[U[i]]<dep[V[i]])ndE[i]=V[i];else ndE[i]=U[i];
	for(int i=1;i<=m;++i){int p,c;scanf("%d%d",&p,&c);w[ndE[p]].push_back(c);}
	dfs_(1,0);
	while(q--)
	{
		int s,t,x;ll y;scanf("%d%d%d%lld",&s,&t,&x,&y);
		int l=lca(s,t);ll Dis=dis[s]+dis[t]-dis[l]-dis[l];
		int id=bin(rt[s],rt[t],rt[l],rt[l],Dis-y-1,1,1e9);
		int num=query(id,1e9,1,1e9,rt[s])+query(id,1e9,1,1e9,rt[t])-2*query(id,1e9,1,1e9,rt[l]);
		if(num>x)printf("-1\n");else printf("%d\n",x-num);
	}return 0;
}