#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;
#define ff first
#define ss second
#define ll int64_t
#define ld long double
#define nl cout<<"\n"
#define i128 __int128_t
#define all(v) v.begin(),v.end()
#define mset(a,v) memset((a),(v),sizeof(a))
#define forn(i,a,b) for(int64_t i=int64_t(a);i<int64_t(b);++i)
#define forb(i,a,b) for(int64_t i=int64_t(a);i>=int64_t(b);--i)
#define fastio() ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define mod 1'000'000'007
#define mod2 998'244'353
#define inf 1'000'000'000'000'007
#define pi 3.14159265358979323846
template<class key,class cmp=std::less<key>>
using ordered_set=tree<key,null_type,cmp,rb_tree_tag,tree_order_statistics_node_update>;
template<class L,class R> ostream& operator<<(ostream& out,pair<L,R> &p) {return out<<"("<<p.ff<<", "<<p.ss<<")";}
template<class T> ostream& operator<<(ostream& out,vector<T> &v) {out<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())out<<", ";out<<*it;}return out<<"]";}
template<class T> ostream& operator<<(ostream& out,deque<T> &v) {out<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())out<<", ";out<<*it;}return out<<"]";}
template<class T> ostream& operator<<(ostream& out,set<T> &s) {out<<"{";for(auto it=s.begin();it!=s.end();++it){if(it!=s.begin())out<<", ";out<<*it;}return out<<"}";}
template<class T> ostream& operator<<(ostream& out,ordered_set<T> &s) {out<<"{";for(auto it=s.begin();it!=s.end();++it){if(it!=s.begin())out<<", ";out<<*it;}return out<<"}";}
template<class L,class R> ostream& operator<<(ostream& out,map<L,R> &m) {out<<"{";for(auto it=m.begin();it!=m.end();++it){if(it!=m.begin())out<<", ";out<<*it;}return out<<"}";}
void dbg_out() {cerr<<"]\n";}
template<typename Head,typename... Tail>
void dbg_out(Head H,Tail... T) {cerr<<H;if(sizeof...(Tail))cerr<<", ";dbg_out(T...);}
#ifdef LOCAL
#define dbg(...) cerr<<"["<<#__VA_ARGS__<<"] = [",dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif
//---------------------------------mars4---------------------------------
int main()
{
fastio();
ll z,n,m,t,k,i,j,l,d,h,r;
const ll logN=20;
ll q;
cin>>k>>n>>m>>q;
ll N=(n+k-1)/k;
vector val(N,vector(logN,vector(k,vector(k,(ll)inf))));
vector jmp(N,vector(logN,(ll)0));
jmp[N-1][0]=N-1;
forn(i,0,N-1)
{
jmp[i][0]=i+1;
}
forn(i,0,m)
{
cin>>l>>r>>d;
val[l/k][0][l%k][r%k]=d;
}
auto combine=[&](vector<vector<ll>> a,vector<vector<ll>> b)
{
vector<vector<ll>> res(k,vector<ll>(k,inf));
forn(i,0,k)
{
forn(j,0,k)
{
forn(h,0,k)
{
res[i][h]=min(res[i][h],a[i][j]+b[j][h]);
}
}
}
return res;
};
forn(j,1,logN)
{
forn(i,0,N)
{
jmp[i][j]=jmp[jmp[i][j-1]][j-1];
val[i][j]=combine(val[i][j-1],val[jmp[i][j-1]][j-1]);
}
}
auto calc=[&](ll l,ll r)
{
ll jumps=r/k-l/k;
if(!jumps)
{
return (ll)-1;
}
vector res(k,vector(k,(ll)inf));
forn(i,0,k)
{
res[i][i]=0;
}
ll ind=l/k;
forb(i,logN-1,0)
{
if(jumps&(1ll<<i))
{
res=combine(res,val[ind][i]);
ind=jmp[ind][i];
}
}
ll ans=res[l%k][r%k];
if(ans>=inf)
{
ans=-1;
}
return ans;
};
while(q--)
{
cin>>l>>r;
cout<<calc(l,r)<<"\n";
}
cerr<<"\nTime elapsed: "<<1000*clock()/CLOCKS_PER_SEC<<"ms\n";
return 0;
}
