#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define fr(j, l,n) for(int j = l; j < int(n); j++)
#define fn(j,n,l) for(int j=n-1;j>=l;j--)
#define gets(s) string s; cin>>s;
#define all(v) v.begin(),v.end()
#define getv(v,n) vector<ll> v(n); fr(i,0,n) cin >> v[i];
#define seev(a) for(auto x:a){cout<<x<<" ";}cout<<endl;
#define vl vector<ll>
#define ve vector
#define vvl vector<vector<ll>>
#define vp vector<pair<ll,ll>>
#define vc vector<char>
#define vvc vector<vector<char>>
#define pb push_back
#define mp make_pair
#define mse multiset<ll>
#define se set<ll>
#define ma map<ll,ll>
#define getmat(v,n,m) vector<vl>v(n,vl(m));fr(i,0,n) {fr (j,0,m) cin>>v[i][j];}
#define seemat(mat) for(auto row:mat){seev(row);}
#define YES cout<<"YES\n";
#define NO cout<<"NO\n";
using namespace std;
using namespace __gnu_pbds;
// Define ordered multiset with long long
typedef tree<long long, long long, less<long>, rb_tree_tag, tree_order_statistics_node_update> ordered_multimap;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
vl sieve;
void SieveOfEratosthenes(int n)
{
// Create a boolean array "prime[0..n]" and initialize
// all entries it as true. A value in prime[i] will
// finally be false if i is Not a prime, else true.
vl prime(n+1,true);
for (int p = 2; p * p <= n; p++) {
// If prime[p] is not changed, then it is a prime
if (prime[p] == true) {
// Update all multiples of p greater than or
// equal to the square of it numbers which are
// multiple of p and are less than p^2 are
// already been marked.
for (int i = p * p; i <= n; i += p)
prime[i] = false;
}
}
// Print all prime numbers
for (int p = 2; p <= n; p++)
if (prime[p])
sieve.push_back(p);
}
bool sortbysec(const pair<ll, ll>& a,
const pair<ll, ll>& b)
{
return (a.second < b.second);
}
// gives gcd and the other coefficients
ll gcd(ll a, ll b, ll& x, ll& y) {
if (b == 0) {
x = 1;
y = 0;
return a;
}
ll x1, y1;
ll d = gcd(b, a % b, x1, y1);
x = y1;
y = x1 - y1 * (a / b);
return d;
}
// a raised to power b
ll pwr(ll a, ll b, ll mod = 0){
ll result = 1;
if(mod == 0){
while(b){
if(b & 1) result *= a;
a *= a;
b = b >> 1;
}
}
else {
while(b){
if(b & 1){
result *= a;
result = result % mod;
}
a *= a;
a = a % mod;
b = b >> 1;
}
}
return result;
}
ll modularinverse(ll a,ll p)// p is prime
{
return pwr(a,p-2,p);
}
// to convert string to binary(63 bits)
string tobin(ll a)
{
string s;
for (int i = 0; i < 63; i++)
{
if(a%2==1)
{
s+='1';
}
else
{
s+='0';
}
a>>=1;
}
return s;
}
int log2_floor(unsigned long long i) {
return i ? 63 - __builtin_clzll(i) : -1;
// -1 as log undefined for 0
}
// QUESTION DHANG SE PADHNA
void combine(vvl &a, vvl &b, ll &k, vvl &c)
{
for (int i = 0; i < k; i++)
{
for (int j = 0; j < k; j++)
{
for (int jj = 0; jj < k; jj++)
{
c[i][j]=min(c[i][j],a[i][jj]+b[jj][j]);
}
}
}
}
void solve(ll tc){
ll n=0,m=0,k=0,a=0,b=0,c=0,x=0,y=0,z=0,o;
cin>>k>>n>>m>>o;
ve<vp> gr(n);
ve<ve<vvl>>dist(n,ve<vvl> (log2_floor(n)+1,vvl(5,vl(5,1e18))));
for (int i = 0; i < m; i++)
{
cin>>a>>b>>x;
// gr[a].pb({b,x});
dist[a/k][0][a%k][b%k]=x;
}
// cout<<'w'<<endl;
for(int j=0;j<dist[0].size()-1;j++)
{
for (int i = 0; i < n/k; i++)
{
if((i+(1<<(j)))<n)
{
// cout<<i<<' '<<(1<<j)<<endl;
combine(dist[i][j],dist[(i+(1<<(j)))][j],k,dist[i][j+1]);
}
}
}
// for (int i = 0; i < n; i++)
// {
// cout<<i<<' '<<endl;
// // vvl ans(k,vl(k,1e18));
// // combine(dist[i][0],dist[i+1][0],k,ans);
// // seemat(ans);
// // cout<<endl;
// seemat(dist[i][1]);
// }
for (int i = 0; i < o; i++)
{
cin>>x>>y;
vvl ans(k,vl(k, 1e18));
vvl ans2(k,vl(k, 1e18));
for (int i = 0; i < k; i++)
{
ans2[i][i]=0;
}
c=x/k,z=y/k;
ll inix=x,iniy=y;
for (int j = 0; j < dist[0].size(); j++)
{
// cout<<z<<' '<<c<<endl;
if(((z-c) & (1<<j)))
{
combine(ans2,dist[c][j],k,ans);
// x+=1<<j;
c+=(1<<j);
swap(ans2,ans);
for (int jj = 0; jj < k; jj++)
{
for (int ii = 0; ii < k; ii++)
{
ans[jj][ii]=1e18;
}
}
}
}
// seemat(ans2);
if(inix/k==iniy/k)
{
cout<<-1<<endl;
}
else
{
if(ans2[inix%k][iniy%k]==1e18)
{
cout<<-1<<endl;
}
else
{
cout<<ans2[inix%k][iniy%k]<<endl;
}
}
}
}
int main(){
#ifndef ONLINE_JUDGE
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int t=1;
// cin>>t;
ll tc=0;
while(t--){
tc++;
solve(tc);
}
return 0;
}
