#include <algorithm>
#include <iostream>
#include <cstring>
#define pb push_back
#define fi first
#define se second
typedef long long ll;
using namespace std;
const int N = 50005;
const int INF = 1e9;
int k, n, m, o;
int dp[N][17][5][5]; // kA + x -> (kA + 2^i) + y
int ans[5][5], tmp[5][5];
void combine(int tar[5][5], int a[5][5], int b[5][5]) {
for (int x = 0; x < k; x++) {
for (int y = 0; y < k; y++) {
for (int z = 0; z < k; z++) {
tar[x][y] = min(tar[x][y], a[x][z] + b[z][y]);
// dp[i][j][x][y] = min dp[i][j - 1][x][z] + dp[i + (1 << j - 1)][j - 1][z][y])
// min cost (ki + x) -> (ki+2^j + y) = min (ki + x) -> (ki+2^j-1 + z) + (ki+2^j-1 + z) -> (ki+2j + y)
}
}
}
}
void solve() {
cin >> k >> n >> m >> o;
memset(dp, 0x3f, sizeof dp);
for (int i = 0; i < m; i++) {
int a, b, c;
cin >> a >> b >> c;
dp[a / k][0][a % k][b % k] = c;
}
for (int j = 1; j < 17; j++) {
for (int i = 0; i + (1 << j) < (n + k - 1) / k; i++) {
combine(dp[i][j], dp[i][j - 1], dp[i + (1 << (j - 1))][j - 1]);
}
}
while (o--) {
int a, b;
cin >> a >> b;
memset(ans, 0x3f, sizeof ans);
for (int i = 0; i < 5; i++) ans[i][i] = 0;
for (int cur = a / k, dest = b / k, i = 16; i >= 0; i--) {
if (cur + (1 << i) <= dest) {
for (int x = 0; x < 5; x++) {
for (int y = 0; y < 5; y++) {
tmp[x][y] = INF;
}
}
combine(tmp, ans, dp[cur][i]);
for (int x = 0; x < 5; x++) {
for (int y = 0; y < 5; y++) {
ans[x][y] = tmp[x][y];
}
}
cur += (1 << i);
}
}
cout << (ans[a % k][b % k] >= 1e9 ? -1 : ans[a % k][b % k]) << '\n';
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
