#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

ifstream fin("amenzi.in");
ofstream fout("amenzi.out");

const int TMax = 3505;
const int NMax = 155;
vector < pair < int, int > > G[NMax];
int dp[TMax][NMax];//best in timpul t pana in intersectia j
int amenda[TMax][NMax];
int N, M, K, P;

void Read()
{
    fin >> N >> M >> K >> P;
    for(int i=1; i<=M; ++i)
    {
        int x, y, c;
        fin >> x >> y >> c;
        G[x].push_back({y,c});
        G[y].push_back({x,c});
    }

    for(int i=1; i<=K; ++i)
    {
        int nod, t, val;
        fin >> nod >> t >> val;
        amenda[t][nod] += val;
    }
}

void Solve()
{
    memset(dp,-1,sizeof(dp));
    dp[0][1] = 0;

    for(int t=0; t < TMax; ++t)
    {
        for(int i=1; i <= N; ++i)
        {
            if(t==0 && i==1)
                continue;

            if(t>=1 && dp[t-1][i] != -1)
                dp[t][i] = dp[t-1][i] + amenda[t][i];

            vector < pair < int, int > > ::iterator it;

            for(it=G[i].begin(); it!=G[i].end(); ++it)
            {
                int itr = it->first;
                int cst = it->second;

                if(t >= cst && dp[t - cst][itr] !=-1)
                    dp[t][i] = max(dp[t][i], dp[t-cst][itr] + amenda[t][i]);

            }

        }
    }
}

void Print()
{
    for(int i=1; i<=P; ++i)
    {
        int nod, timp;
        fin >> nod >> timp;
        fout << dp[timp][nod] << "\n";
    }
}

int main()
{
    Read();
    Solve();
    Print();
    return 0;
}