#include <cstdio>
#include <cstdlib>
#include <ctime>
using namespace std;

const char iname[] = "amenzi.in";
const char oname[] = "amenzi.out";

#define MAX_N 151
#define MAX_T 3501

int G[MAX_N][MAX_N], D[MAX_N][MAX_N], deg[MAX_N];

int A[MAX_T][MAX_N];

int R[MAX_T][MAX_N], in[MAX_T][MAX_N];


int solve(int T, int X, int n)
{
	if ((T == 0) && (X == 1)) {
		R[T][X]  = 0;
		in[T][X] = 1;
	}
	if (in[T][X])
		return R[T][X];

	R[T][X] = -1;

	if (T > 0)
		R[T][X] = solve(T - 1, X, n);
	for (int i = 0; i < deg[X]; ++i) {
		int Y = G[X][i];
		int C = D[X][i];
		if (T >= C) {
			solve(T - C, Y, n);
			if (R[T][X] < R[T - C][Y])
				R[T][X] = R[T - C][Y];
		}
	}
	if (R[T][X] != -1)
		R[T][X] += A[T][X];
	in[T][X] = 1;
	return R[T][X];
}

int main(void) 
{
	freopen(iname, "r", stdin);
	int N, M;
	int K, P;
	int X, Y, C, T;

	scanf("%d %d %d %d", &N, &M, &K, &P);
	for (int i = 0; i < M; ++i) {
		scanf("%d %d %d", &X, &Y, &C);
		G[X][deg[X]] = Y, D[X][deg[X]] = C;
		deg[X] ++;
		G[Y][deg[Y]] = X, D[Y][deg[Y]] = C;
		deg[Y] ++;
	}
	for (int i = 0; i < K; ++i) {
		scanf("%d %d %d", &X, &T, &C);
		A[T][X] += C;
	}
	for (T = 0; T < MAX_T; ++T)
		for (X = 1; X <= N; ++X)
			solve(T, X, N);
	
	freopen(oname, "w", stdout);
	
	for (int i = 0; i < P; ++i) {
		scanf("%d %d", &X, &T);
		printf("%d\n", R[T][X]);
	}
	return 0;
}