#include <bits/stdc++.h>
#define mp make_pair
#define all(a) a.begin(), a.end()
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;
typedef vector<vector<ll> > vvi;
int k;
vvi combine(vvi beg, vvi endd) {
vvi ans(k, vector<ll>(k, 1e18));
for (int i = 0; i < k; i++)
for (int j = 0; j < k; j++)
for (int l = 0; l < k; l++)
ans[i][l] = min(ans[i][l], beg[i][j] + endd[j][l]);
return ans;
}
const int lg = 18;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, m, q;
cin >> k >> n >> m >> q;
vector<vector<vvi> > lift(lg, vector<vvi> (n / k + 1, vvi(k, vector<ll>(k, 1e18))));
for (int i = 0; i < m; i++) {
int f, t, p;
cin >>f >> t >> p;
lift[0][f / k][f % k][t % k] = p;
}
int num_lay = n / k + 1;
for (int bit = 1; bit < lg; bit++)
for (int i = num_lay - (1 << (bit - 1)) - 1; i >= 0; i--)
lift[bit][i] = combine(lift[bit - 1][i], lift[bit - 1][i + (1 << (bit - 1))]);
while (q--) {
int f, t;
cin >> f >> t;
int SF = f / k, ST = t / k;
vvi ans(k, vector<ll>(k, 1e18));
ans[f % k][f % k] = 0;
int diff = ST - SF;
for (int i = 0; i < lg; i++) {
if (((1 << i) & diff) != 0) {
ans = combine(ans, lift[i][SF]);
SF += (1 << i);
}
}
if (ans[f % k][t % k] == 1e18)
cout << "-1\n";
else
cout << ans[f % k][t % k] << "\n";
}
}
