#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define pb push_back
#define mp make_pair
#define f first
#define s second
int k, n, m, o;
int ans[5][5], temp[5][5], dp[50000][17][5][5];
void combine(int t[5][5], int a[5][5], int b[5][5]){
for(int i = 0; i < k; i++){
for(int j = 0; j < k; j++){
for(int l = 0; l < k; l++){
t[i][j] = min(t[i][j], a[i][l] + b[l][j]);
}
}
}
}
void solve(){
cin >> k >> n >> m >> o;
memset(dp, 0x3f, sizeof dp);
while (m--) {
int a, b, t;
cin >> a >> b >> t;
dp[a / k][0][a % k][b % k] = t;
}
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 curr = a / k, dest = b / k, i = 16; ~i; i--) {
if (curr + (1 << i) <= dest) {
memset(temp, 0x3f, sizeof temp);
combine(temp, ans, dp[curr][i]);
memcpy(ans, temp, sizeof ans);
curr += (1 << i);
}
}
cout << (ans[a % k][b % k] == 0x3f3f3f3f ? -1 : ans[a % k][b % k])
<< '\n';
}
}
int main(){
//freopen("infasuratoare.in", "r", stdin);
//freopen("infasuratoare.out", "w", stdout);
ios::sync_with_stdio(0); cin.tie(0);
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
