#include <bits/stdc++.h>
using namespace std;

#define int long long

struct node
{
	int lc,rc,sz,sum;
};

const int N=1e5+5;

node res[N*35];
vector <int> g[N],vec[N];
int x[N],y[N],fa[N][25],dep[N],rt[N],cnt;

void dfs1(int x)
{
	for(int i=1;i<20;i++)
		fa[x][i]=fa[fa[x][i-1]][i-1];

	for(auto to:g[x])
		if(to!=fa[x][0])
			dep[to]=dep[x]+1, fa[to][0]=x, dfs1(to);
}

int update(int x,int l,int r,int y)
{
	int rt=++cnt;
	res[rt]=res[x], res[rt].sz++, res[rt].sum += y;
	if(l==r)
		return rt;

	int mid=(l+r)/2;
	if(y<mid)
		res[rt].lc=update(res[x].lc,l,mid,y);
	else
		res[rt].rc=update(res[x].rc,mid+1,r,y);
	return rt;
}

void dfs2(int x)
{
	if(fa[x][0])
		rt[x]=rt[fa[x][0]];

	for(auto y:vec[x])
		rt[x]=update(rt[x],0,1000000000,y);

	for(auto to:g[x])
		if(to!=fa[x][0])
			dfs2(to);
}

int lca(int x,int y)
{
	if(dep[x]<dep[y])
		swap(x,y);

	for(int i=19;i>=0;i--)
		if(dep[fa[x][i]]>=dep[y])
			x=fa[x][i];

	if(x==y)
		return x;

	for(int i=19;i>=0;i--)
		if(fa[x][i]!=fa[y][i])
			x=fa[x][i], y=fa[y][i];

	return fa[x][0];
}

int query(int rt1,int rt2,int rt3,int l,int r,int sum)
{
	if(l==r)
	{
		if(l==0)
			return res[rt1].sz+res[rt2].sz-res[rt3].sz*2;
		else
			return min(res[rt1].sz+res[rt2].sz-res[rt3].sz*2,sum/l);
	}

	int mid=(l+r)/2, lsum=res[res[rt1].lc].sum+res[res[rt2].lc].sum-res[res[rt3].lc].sum*2;
	if(lsum<sum)
		return res[res[rt1].lc].sz+res[res[rt2].lc].sz-res[res[rt3].lc].sz*2+query(res[rt1].rc,res[rt2].rc,res[rt3].rc,mid+1,r,sum-lsum);
	return query(res[rt1].lc,res[rt2].lc,res[rt3].lc,l,mid,sum);
}

signed main()
{
	int n,m,q;
	cin >> n >> m >> q;
	for(int i=1;i<n;i++)
	{
		scanf("%lld %lld",&x[i],&y[i]);
		g[x[i]].push_back(y[i]);
		g[y[i]].push_back(x[i]);
	}

	dep[1]=1;
	dfs1(1);

	for(int i=1;i<=m;i++)
	{
		int p,c;
		scanf("%lld %lld",&p,&c);
		if(fa[x[p]][0]==y[p])
			vec[x[p]].push_back(c);
		else
			vec[y[p]].push_back(c);
	}

	dfs2(1);

	for(int i=1;i<=q;i++)
	{
		int s,t,x,y;
		scanf("%lld %lld %lld %lld",&s,&t,&x,&y);
		int LCA=lca(s,t);
		int mincost=res[rt[s]].sz+res[rt[t]].sz-res[rt[LCA]].sz*2-query(rt[s],rt[t],rt[LCA],0,1000000000,y);
		if(mincost>x)
			printf("-1\n");
		else
			printf("%lld\n",x-mincost);
	}
	return 0;
}