#include <cstdio>

#include <algorithm>

#define N 40010

using namespace std;

struct data

{

	int x , y , z , v , w;

	data() {}

	data(int a , int b , int c , int d , int e) {x = a , y = b , z = c , v = d , w = e;}

	bool operator<(const data &a)const {return x < a.x;}

}a[N * 3] , q[N * 2] , t[N * 2];

int n , head[N] , to[N << 1] , next[N << 1] , cnt , fa[N][20] , deep[N] , log[N] , pos[N] , last[N] , tp , tot , f[N] , val[N] , cc[N] , ans[N];

bool cmp(const data &a , const data &b)

{

	return a.v < b.v;

}

inline void add(int x , int y)

{

	to[++cnt] = y , next[cnt] = head[x] , head[x] = cnt;

}

void dfs(int x)

{

	int i;

	pos[x] = ++tp;

	for(i = 1 ; (1 << i) <= deep[x] ; i ++ ) fa[x][i] = fa[fa[x][i - 1]][i - 1];

	for(i = head[x] ; i ; i = next[i])

		if(to[i] != fa[x][0])

			fa[to[i]][0] = x , deep[to[i]] = deep[x] + 1 , dfs(to[i]);

	last[x] = tp;

}

int find(int x , int y)

{

	int i;

	for(i = log[y] ; ~i ; i -- )

		if((1 << i) <= y)

			x = fa[x][i] , y -= (1 << i);

	return x;

}

inline void update(int x , int a)

{

	int i;

	for(i = x ; i <= n ; i += i & -i) f[i] += a;

}

inline int query(int x)

{

	int i , ans = 0;

	for(i = x ; i ; i -= i & -i) ans += f[i];

	return ans;

}

void solve(int b , int e , int l , int r , int L , int R)

{

	if(b > e) return;

	int i;

	if(L == R)

	{

		for(i = b ; i <= e ; i ++ ) ans[q[i].z] = L;

		return;

	}

	int MID = (L + R) >> 1 , mid = l - 1 , p = l;

	for(i = b ; i <= e ; i ++ ) cc[q[i].z] = 0;

	sort(a + l , a + r + 1 , cmp);

	while(mid < r && a[mid + 1].v <= MID) mid ++ ;

	sort(a + l , a + mid + 1);

	for(i = b ; i <= e ; i ++ )

	{

		while(p <= mid && a[p].x <= q[i].x) update(a[p].y , a[p].w) , update(a[p].z + 1 , -a[p].w) , p ++ ;

		cc[q[i].z] += query(q[i].y);

	}

	while(p > l) p -- , update(a[p].y , -a[p].w) , update(a[p].z + 1 , a[p].w);

	for(p = i = b ; i <= e ; i ++ ) if(val[q[i].z] <= cc[q[i].z]) t[p ++ ] = q[i];

	for(p = i = e ; i >= b ; i -- ) if(val[q[i].z] > cc[q[i].z]) t[p -- ] = q[i];

	for(i = b ; i <= e ; i ++ )

	{

		if(~cc[q[i].z] && val[q[i].z] > cc[q[i].z]) val[q[i].z] -= cc[q[i].z] , cc[q[i].z] = -1;

		q[i] = t[i];

	}

	solve(b , p , l , mid , L , MID) , solve(p + 1 , e , mid + 1 , r , MID + 1 , R);

}

int main()

{

	int m , k , i , x , y , z , t;

	scanf("%d%d%d" , &n , &m , &k);

	for(i = 2 ; i <= n ; i ++ ) scanf("%d%d" , &x , &y) , add(x , y) , add(y , x) , log[i] = log[i >> 1] + 1;

	dfs(1);

	for(i = 1 ; i <= m ; i ++ )

	{

		scanf("%d%d%d" , &x , &y , &z);

		if(deep[x] > deep[y]) swap(x , y);

		if(deep[x] < deep[y] && fa[t = find(y , deep[y] - deep[x] - 1)][0] == x)

		{

			a[++tot] = data(1 , pos[y] , last[y] , z , 1);

			a[++tot] = data(pos[t] , pos[y] , last[y] , z , -1);

			a[++tot] = data(last[t] + 1 , pos[y] , last[y] , z , 1);

		}

		else a[++tot] = data(pos[x] , pos[y] , last[y] , z , 1) , a[++tot] = data(last[x] + 1 , pos[y] , last[y] , z , -1);

	}

	for(i = 1 ; i <= k ; i ++ ) scanf("%d%d%d" , &x , &y , &val[i]) , q[i] = data(pos[x] , pos[y] , i , 0 , 0) , q[i + k] = data(pos[y] , pos[x] , i , 0 , 0);

	sort(q + 1 , q + k * 2 + 1) , solve(1 , k * 2 , 1 , tot , 1 , 1000000000);

	for(i = 1 ; i <= k ; i ++ ) printf("%d\n" , ans[i]);

	return 0;

}