#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;
}