#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<int, int> pii;
typedef pair<ld, ld> pld;
int k, n, m, o;
vector<pii> g[50009];
vector<int> dis[50009][17];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> k >> n >> m >> o;
while(m--){
int x, y, z;
cin >> x >> y >> z;
g[x].pb({y, z});
}
for(int i = n-1; i >= 0; --i){
dis[i][0] = vector<int>(k, 1e9);
for(auto u : g[i]){
dis[i][0][u.ff%k] = u.ss;
//cout << i << ' ' << u.ff%k << '\n';
}
for(int j = 1; j < 17; ++j){
dis[i][j] = vector<int>(k, 1e9);
for(int mn = 0; mn < k; ++mn)
for(int en = 0; en < k; ++en){
int mval = (i/k+(1<<(j-1)))*k+mn;
if(mval <= n-1)
dis[i][j][en] = min(dis[i][j][en], dis[i][j-1][mn]+dis[mval][j-1][en]);
}
}
}
while(o--){
int x, y;
cin >> x >> y;
vector<int> d(k, 1e9);
d[x%k] = 0;
int beg = x/k;
int end = y/k;
for(int i = 16; i >= 0; --i){
if(beg + (1<<i) > end) continue;
vector<int> nd(k, 1e9);
for(int mn = 0; mn < k; ++mn){
int mval = beg*k+mn;
for(int en = 0; en < k; ++en)
nd[en] = min(nd[en], d[mn]+dis[mval][i][en]);
}
beg += (1<<i);
d = nd;
}
if(d[y%k] == 1e9)
cout << "-1\n";
else
cout << d[y%k] << '\n';
}
}
