#include <fstream>
#include <algorithm>
#include <vector>
#include <cassert>
#include <cmath>
#include <stack>
#include <set>
#include <functional>
#include <bitset>
#include <map>
#include <unordered_map>
#include <queue>
using namespace std;
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename A> ostream& operator<<(ostream &os, vector<A>&a) { for(auto &c:a)os<<c<<' '; return os;}
template<typename A> istream& operator>>(istream  &os, vector<A>&a) { for(auto &c:a)os>>c; return os;}
template<typename A,size_t N> istream& operator>>(istream &os, array<A,N>&a) { for(auto &c:a)os>>c; return os;}
#define bug(a) cerr << "(" << #a << ": " << a << ")\n";
#define all(x) x.begin(),x.end()
#define pb push_back
#define PQ priority_queue
#define pii pair<int,int>
using i64= int64_t;
using i16= int16_t;
using u64= uint64_t;
using u32= uint32_t;
using i32= int32_t;
using u16= uint16_t;
const i32 inf=1e9;
const i64 INF=1e18;
const int mod=1e9+7;
const int T=3'500;
ifstream cin("amenzi.in");
ofstream cout("amenzi.out");
void solve()
{
    int n,m,k,q;
    cin>>n>>m>>k>>q;
    vector<vector<pair<int,int>>>g(n);
    for(int i=0;i<m;i++)
    {
        int x,y,z;
        cin>>x>>y>>z;
        x--;
        y--;
        g[x].pb({y,z});
        g[y].pb({x,z});
    }
    vector<vector<int>>dp(T+1,vector<int>(n,-inf));
    vector<vector<int>>cost(T+1,vector<int>(n,0));
    fill(all(dp[0]),-inf);
    dp[0][0]=0;
    for(int i=0;i<k;i++)
    {
        int x,y,z;
        cin>>x>>y>>z;
        cost[y][--x]=z;
    }
    for(int i=1;i<=T;i++)
    {
        dp[i]=dp[i-1];
        for(int j=0;j<n;j++)
        {
            for(auto &c:g[j])
            {
                if(i>=c.second && dp[ i-c.second ][ c.first ]>=0)
                {
                    dp[i][j] = max(dp[i][j] , dp[ i-c.second ][c.first]+cost[i][j]);
                }
            }
        }
    }
    while(q--)
    {
        int x,y;
        cin>>x>>y;
        cout<<dp[y][x-1]<<'\n';
    }
}
int main()
{
    auto sol=[&](bool x)
    {
        if(x)return "YES\n";
        return "NO\n";
    };
    i32 tt=1;
    ios::sync_with_stdio(false);
    cin.tie(0);
    //cin>>tt;
    while(tt--)
    {
        solve();
    }
}