#include <bits/stdc++.h>
// cut here
#ifdef _MSC_VER
#include <intrin.h>
#endif
namespace atcoder {
namespace internal {
int ceil_pow2(int n) {
int x = 0;
while ((1U << x) < (unsigned int)(n)) x++;
return x;
}
int bsf(unsigned int n) {
#ifdef _MSC_VER
unsigned long index;
_BitScanForward(&index, n);
return index;
#else
return __builtin_ctz(n);
#endif
}
} // namespace internal
} // namespace atcoder
namespace atcoder {
template <class S, S (*op)(S, S), S (*e)()> struct segtree {
public:
segtree() : segtree(0) {}
segtree(int n) : segtree(std::vector<S>(n, e())) {}
segtree(const std::vector<S>& v) : _n(int(v.size())) {
log = internal::ceil_pow2(_n);
size = 1 << log;
d = std::vector<S>(2 * size, e());
for (int i = 0; i < _n; i++) d[size + i] = v[i];
for (int i = size - 1; i >= 1; i--) {
update(i);
}
}
void set(int p, S x) {
assert(0 <= p && p < _n);
p += size;
d[p] = x;
for (int i = 1; i <= log; i++) update(p >> i);
}
S get(int p) {
assert(0 <= p && p < _n);
return d[p + size];
}
S prod(int l, int r) {
assert(0 <= l && l <= r && r <= _n);
S sml = e(), smr = e();
l += size;
r += size;
while (l < r) {
if (l & 1) sml = op(sml, d[l++]);
if (r & 1) smr = op(d[--r], smr);
l >>= 1;
r >>= 1;
}
return op(sml, smr);
}
S all_prod() { return d[1]; }
template <bool (*f)(S)> int max_right(int l) {
return max_right(l, [](S x) { return f(x); });
}
template <class F> int max_right(int l, F f) {
assert(0 <= l && l <= _n);
assert(f(e()));
if (l == _n) return _n;
l += size;
S sm = e();
do {
while (l % 2 == 0) l >>= 1;
if (!f(op(sm, d[l]))) {
while (l < size) {
l = (2 * l);
if (f(op(sm, d[l]))) {
sm = op(sm, d[l]);
l++;
}
}
return l - size;
}
sm = op(sm, d[l]);
l++;
} while ((l & -l) != l);
return _n;
}
template <bool (*f)(S)> int min_left(int r) {
return min_left(r, [](S x) { return f(x); });
}
template <class F> int min_left(int r, F f) {
assert(0 <= r && r <= _n);
assert(f(e()));
if (r == 0) return 0;
r += size;
S sm = e();
do {
r--;
while (r > 1 && (r % 2)) r >>= 1;
if (!f(op(d[r], sm))) {
while (r < size) {
r = (2 * r + 1);
if (f(op(d[r], sm))) {
sm = op(d[r], sm);
r--;
}
}
return r + 1 - size;
}
sm = op(d[r], sm);
} while ((r & -r) != r);
return 0;
}
private:
int _n, size, log;
std::vector<S> d;
void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};
} // namespace atcoder
// cut here
#define int ll
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define rng(i,c,n) for(int i=c;i<n;i++)
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define vec(...) vector<__VA_ARGS__>
#define _3TBjhXk ios::sync_with_stdio(0),cin.tie(0)
typedef long long ll;
using pii=pair<int,int>;
using vi=vector<int>;
void print(){cout<<'\n';}
template<class h,class...t>
void print(const h&v,const t&...u){cout<<v<<' ',print(u...);}
const int inf=1e10;
struct dat{
int frl,bkl; // front level, back level
int res[5][5];
dat(){
rep(i,5){
rep(j,5){
res[i][j]=inf;
}
}
}
};
int k,n,m,q;
int es[50011][5][5];
dat op(const dat l,const dat r){
if(l.bkl==-1) return r;
if(r.frl==-1) return l;
dat res;
res.frl=l.frl;
res.bkl=r.bkl;
int frm=l.bkl;
int to=r.frl;
rep(j0,k){
rep(j1,k){
rep(j2,k){
rep(j3,k){
// j0 is l.frl
// j1 and j2 should merge
// j3 is r.bkr
res.res[j0][j3]=min(res.res[j0][j3],l.res[j0][j1]+r.res[j2][j3]+es[l.bkl][j1][j2]);
}
}
}
}
return res;
}
dat _e;
dat e(){
return _e;
}
signed main(){
_3TBjhXk;
cin>>k>>n>>m>>q;
rep(i,n){
rep(j0,k){
rep(j1,k){
es[i][j0][j1]=inf;
}
}
}
rep(j0,k){
rep(j1,k){
_e.bkl=-1;
_e.frl=-1;
_e.res[j0][j1]=inf;
}
}
rep(i,m){
int u,v,w;
cin>>u>>v>>w;
// print(u/k,u%k,v%k,w);
es[(u/k)][u%k][v%k]=w;
}
atcoder::segtree<dat,op,e> seg(n/k+1);
for(int i=0;i<n;i+=k){
dat now;
now.frl=i/k;
now.bkl=i/k;
for(int j=i;j<min(n,i+k);j++){
now.res[j%k][j%k]=0;
}
seg.set(i/k,now);
}
rep(_,q){
int u,v;
cin>>u>>v;
int ans=inf;
if(u/k!=v/k){
dat now=seg.prod(u/k,v/k+1);
ans=now.res[u%k][v%k];
}
print(ans==inf?-1:ans);
}
}
