/*
AUTHOR : BELGIANBOT
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> void read(T& x) { cin >> x;}
template<typename T1, typename T2> void read(pair<T1, T2>& p) { read(p.first), read(p.second);}
template<typename T> void read(vector<T>& v) { for (auto& x : v) read(x); }
template<typename T1, typename T2> void read(T1& x, T2& y) { read(x), read(y); }
template<typename T1, typename T2, typename T3> void read(T1& x, T2& y, T3& z) { read(x), read(y), read(z); }
template<typename T1, typename T2, typename T3, typename T4> void read(T1& x, T2& y, T3& z, T4& zz) { read(x), read(y), read(z), read(zz); }
template<typename T> void print(vector<T>& v) { for (auto& x : v) cout << x << ' '; cout << endl; }
#define quit(x) return (void)(cout << x << endl)
#define pb push_back
#define fi first
#define se second
#define ordered_set tree<pair<int,int>, null_type, less<pair<int,int>>, rb_tree_tag, tree_order_statistics_node_update>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define mp make_pair
#define sz(x) (int)(x.size())
#define YES cout<<"YES\n"
#define NO cout<<"NO\n"
#define QYES quit("YES")
#define QNO quit("NO")
#define cmin(a, b) a = min(a, b)
#define cmax(a, b) a = max(a, b)
#define int long long
#define double long double
const int inf = numeric_limits<int>::max() / 4;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int MOD = 1e9+7, LOG=20;
void solve();
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
int t = 1;
//cin >> t;
while (t--) solve();
return 0;
}
int k, n, m, p, q;
vector<vector<pair<int,int>>> adj;
vector<vector<vector<int>>> up;
void solve() {
cin >> k >> n >> m >> q;
adj.resize(n);
up.resize(n,vector<vector<int>>(LOG, vector<int>(k,inf)));
for (int i = 0; i < m; i++) {
int a, b,t; cin >> a >> b >> t;
adj[a].pb({b,t});
}
for (int i = n-1; i >= 0; i--) {
for (auto x : adj[i]) up[i][0][x.fi%k] = x.se;
for (int j = 1; j < LOG; j++) {
for (int l = 0; l < k; l++) {
for (int o = 0; o < k; o++) {
if ((i/k+(1<<j))*k+o >= n) break;
cmin(up[i][j][l], up[i][j-1][o] + up[(i/k+(1<<(j-1)))*k+o][j-1][l]);
}
}
}
}
while (q--) {
int a, b; cin >> a >> b;
if (a + k > b) {
cout << -1 << '\n';
continue;
}
int dist = b/k - a/k;
vector<int> ans(k, inf);
ans[a%k] = 0;
int pos = a/k;
for (int i = 0; i < LOG; i++) {
if (dist & (1<<i)) {
vector<int> newans(k, inf);
for (int j = 0; j < k; j++) {
for (int l = 0; l < k; l++) cmin(newans[j], ans[l] + up[pos*k+l][i][j]);
}
ans = newans;
pos += (1 << i);
}
}
int res = ans[b%k];
if (res == inf) cout << -1 << '\n';
else cout << res << '\n';
}
}
