#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;
#define inf 1<<20
#define nmax 155
#define x first
#define y second
#define intervalmax 3505

ifstream f("amenzi.in");
ofstream g("amenzi.out");


/*struct str
{
    int vecin,cost;
};*/

struct str2
{
    int moment,nod,val;
};

bool cmp(str2 a,str2 b)
{
    return a.moment<b.moment;
}

/*vector<str>Q[nmax];*/
vector<str2>amenzi;
vector<pair<int,int>>query;

int n,m,k,p,cost[nmax][nmax],bestcost[nmax][nmax];
int bestamenda;
int dp[nmax];


void read()
{
    f>>n>>m>>k>>p;
    for (int i=1; i<=n; ++i)
        for (int j=1; j<=n; ++j)
            cost[i][j]=inf;
    for (int i=1; i<=m; ++i)
    {
        int e1,e2,e3;
        f>>e1>>e2>>e3;
        cost[e1][e2]=cost[e2][e1]=e3;
    }
    for (int i=1; i<=k; ++i)
    {
        int e1,e2,e3;
        f>>e1>>e2>>e3;
        amenzi.push_back({e2,e1,e3});
    }
    for (int i=1; i<=p; ++i)
    {
        int e1,e2;
        f>>e1>>e2;
        query.push_back({e1,e2});
    }
}

void floyd_warshall()
{
    for (int i=1; i<=n; ++i)
        cost[i][i]=0;
    for (int k=1; k<=n; ++k)
        for (int i=1; i<=n; ++i)
            for (int j=1; j<=n; ++j)
                cost[i][j]=cost[j][i]=min(cost[j][i],cost[i][k]+cost[k][j]);
}


void solve()
{
    floyd_warshall();
    sort(amenzi.begin(),amenzi.end(),cmp);
    for (auto w:query)
    {
        int intal=w.x;
        int momintal=w.y;
        memset(dp,0,sizeof(dp));
        for (int i=0; i<k; ++i)
        {
            int node=amenzi[i].nod;
            int value=amenzi[i].val;
            int moment=amenzi[i].moment;
            if (moment+cost[node][intal]>momintal)
                break;
            for (int j=0; j<i; ++j)
            {
                int prevnode=amenzi[j].nod;
                int prevmoment=amenzi[j].moment;
                if (prevmoment+cost[prevnode][node]<=moment)
                    dp[i]=max(dp[i],dp[j]);
            }
            if (dp[i]==0)
            {
                if (cost[1][node]<=moment)
                    dp[i]+=value;
            }
            else
                dp[i]+=value;
        }
        int ans=0;
        for (int i=0; i<k; ++i)
            ans=max(ans,dp[i]);
        g<<ans<<'\n';
    }

}

int main()
{
    read();
    solve();
    return 0;
}