#include <cstdio>
using namespace std;

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

#define MAX_N 151
#define MAX_T 3501
#define MAX_P 8000

int G[MAX_N][MAX_N];

int A[MAX_T][MAX_N];

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

int V[MAX_P], T[MAX_P], X[MAX_P], S[MAX_P];


int solve(int t, int i, int n)
{
	if (in[t][i])
		return R[t][i];
	if (t > 0)
		R[t][i] = solve(t - 1, i, n);
	for (int j = 1; j <= n; ++j) {
		if ((G[i][j] > 0) && (t >= G[i][j])) {
			solve(t - G[i][j], j, n);
			if (R[t][i] < R[t - G[i][j]][j])
				R[t][i] = R[t - G[i][j]][j];
		}
	}
	if (R[t][i] != -1)
		R[t][i] += A[t][i];
	in[t][i] = 1;
	return R[t][i];
}

inline void shift(int & a, int & b) {
	a ^= b ^= a ^= b;
}

int main(void) 
{
	freopen(iname, "r", stdin);
	int N, M;
	int K, P;
	int i, j, x, y, c, t;
	for (scanf("%d %d %d %d", &N, &M, &K, &P), i = 0; i < M; ++i) {
		scanf("%d %d %d", &x, &y, &c);
		G[x][y] = G[y][x] = c;
		if (c == 0)
			for (;;);
	}
	for (i = 0; i < K; ++i) {
		scanf("%d %d %d", &x, &t, &c);
		A[t][x] += c;
	}
	for (i = 0; i < P; ++i)
		scanf("%d %d", V + i, T + i);
	for (t = 0; t < MAX_T; ++t)
		for (i = 0; i <= N; ++i)   
			R[t][i] = -1;
	R[0][1] = 0;
	in[0][1] = 1;
	for (i = 0; i < P; ++i)
		X[i] = i;
	for (i = 0; i < P; ++i) {
		for (j = i + 1; j < P; ++j)
			if (T[i] > T[j])
				shift(V[i], V[j]), shift(T[i], T[j]), shift(X[i], X[j]);
	}
	for (i = 0; i < P; ++i) {
		S[X[i]] = solve(T[i], V[i], N);
		R[T[i]][V[i]] = -1;
	}
	freopen(oname, "w", stdout);
	for (i = 0; i < P; ++i)
		printf("%d\n", S[i]);
	return 0;
}