#include <cstdio>
#include <cstdlib>
#include <ctime>
using namespace std;
const char iname[] = "amenzi.in";
const char oname[] = "amenzi.out";
#define MAX_N 155
#define MAX_T 3505
int G[MAX_N][MAX_N];
int A[MAX_T][MAX_N];
int R[MAX_T][MAX_N], in[MAX_T][MAX_N];
int solve(int t, int i, int n)
{
if ((t == 0) && (i == 1)) {
R[t][i] = 0;
in[t][i] = 1;
} else
R[t][i] = -1;
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;
}
void write_out(int n, int m, int k, int p)
{
FILE *fo = fopen(iname, "w");
int i;
int x, y, c;
fprintf(fo, "%d %d %d %d\n", n, m, k, p);
for (i = 0; i < m; ++i) {
x = rand() % MAX_N + 1;
y = rand() % MAX_N + 1;
c = rand() + 1;
fprintf(fo, "%d %d %d\n", x, y, c);
}
for (i = 0; i < k; ++i) {
x = rand() % MAX_N + 1;
y = rand() % MAX_T;
c = rand();
fprintf(fo, "%d %d %d\n", x, y, c);
}
for (i = 0; i < p; ++i) {
x = rand() % MAX_N + 1;
y = rand() % MAX_T;
fprintf(fo, "%d %d\n", x, y);
}
fclose(fo);
}
int main(void)
{
// write_out(150, 1500, 12000, 8000);
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;
}
for (i = 0; i < K; ++i) {
scanf("%d %d %d", &x, &t, &c);
A[t][x] += c;
}
for (t = 0; t < MAX_T; ++t)
for (i = 1; i <= N; ++i)
solve(t, i, N);
freopen(oname, "w", stdout);
for (i = 0; i < P; ++i) {
scanf("%d %d", &x, &t);
printf("%d\n", R[t][x]);
}
return 0;
}