#include<bits/stdc++.h>
#define vc vector
#define pb push_back
#define int long long
using namespace std;
const int N=1e5+5,Lim=18;

inline int read() {
	int x=0,w=0; char ch=getchar();
	while(!isdigit(ch)) w|=(ch=='-'), ch=getchar();
	while(isdigit(ch)) x=x*10+(ch^48), ch=getchar();
	return w?-x:x;
}
inline void write(int x) { if(x>9) write(x/10); putchar(x%10+'0'); }
inline void writee(int x) { write(x); putchar(10); }

int n,m,q,len,b[N];
int d[N],fa[Lim][N];
int hd[N],to[N<<1],ne[N<<1],tc=1;
vc<int> cost[N];

//sgt
int idx,rt[N],ch[N<<5][2],s[N<<5],sz[N<<5];
#define mid (l+r>>1)
#define lc(x) (ch[x][0])
#define rc(x) (ch[x][1])
inline void psu(int k) { sz[k]=sz[lc(k)]+sz[rc(k)]; s[k]=s[lc(k)]+s[rc(k)]; }
inline void ins(int &k,int pre,int l,int r,int p) {
	k=++idx; lc(k)=lc(pre); rc(k)=rc(pre); s[k]=s[pre]; sz[k]=sz[pre];
	if(l==r) return ++sz[k], s[k]+=b[l], void();
	return (p<=mid?ins(lc(k),lc(pre),l,mid,p):ins(rc(k),rc(pre),mid+1,r,p)), psu(k);
}
inline int ask(int x,int y,int z,int l,int r,int v) {
	if(l==r) return max(0ll,sz[x]+sz[y]-2*sz[z]-v/b[l]);
	int res=s[lc(x)]+s[lc(y)]-2*s[lc(z)];
	if(v>=res) return ask(rc(x),rc(y),rc(z),mid+1,r,v-res);
	else return ask(lc(x),lc(y),lc(z),l,mid,v)+(sz[rc(x)]+sz[rc(y)]-2*sz[rc(z)]);
}
//tree
inline void add(int x,int y) { 
	to[++tc]=y; ne[tc]=hd[x]; hd[x]=tc; 
	to[++tc]=x; ne[tc]=hd[y]; hd[y]=tc;
}
inline void dfs(int x) {
	for(int i=1;i<Lim;i++) fa[i][x]=fa[i-1][fa[i-1][x]];
	for(int i=hd[x],y;i;i=ne[i]) if((y=to[i])!=fa[0][x]) {
		fa[0][y]=x; d[y]=d[x]+1;
		rt[y]=rt[x];
		if(cost[i>>1].size()) 
			for(auto u:cost[i>>1]) ins(rt[y],rt[y],1,len,u);
		dfs(y);
	}
}
inline int lca(int x,int y) {
	if(d[x]>d[y]) swap(x,y);
	for(int i=Lim-1;i>=0;i--) if(d[fa[i][x]]>=d[y]) x=fa[i][x];
	if(x==y) return x;
	for(int i=Lim-1;i>=0;i--) if(fa[i][x]^fa[i][y]) x=fa[i][x], y=fa[i][y];
	return fa[0][x];
}
//solve
inline void solve() {
	int s=read(), t=read(), x=read(), y=read();
	int p=lca(s,t);
	int res=ask(rt[s],rt[t],rt[p],1,len,y);
	if(res>x) return puts("-1"), void();
	else writee(x-res);
}

signed main() {
	//freopen("a.in","r",stdin);
	
	n=read(); m=read(); q=read(); b[++len]=0;
	for(int i=1,u,v;i<n;i++) u=read(), v=read(), add(u,v);
	for(int i=1,p;i<=m;i++) p=read(), b[++len]=read(), cost[p].pb(b[len]);
	
	sort(b+1,b+1+len); len=unique(b+1,b+1+len)-b-1;
	for(int i=1;i<=n;i++) 
		for(auto &u:cost[i]) u=lower_bound(b+1,b+1+len,u)-b;
	
	d[1]=1; dfs(1);	
	
	while(q--) solve();
	
	return 0;
}