#include <fstream>
#include <queue>
#include <vector>

#define NMAX 152
#define INF 99999999

using namespace std;

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

int N, M, K;
int tasks;

int place, TAIM;

vector < int > Ad [ NMAX ];
vector < int > Cost [ NMAX ];

vector < int > Infra_time[ NMAX ]; /// ORA AMENZILOR LA FIECARE NOD
vector < int > Infra_pret[ NMAX ]; /// COSTUL AMENZILOR LA FIECARE NOD

int mat[ NMAX ][ 3502 ];

struct Stare
{
  int nod, moment, bani;
} temp;

struct comp
{
  bool operator()( const Stare & A, const Stare & B )
  {
    return A.bani < B.bani;
  }
};

priority_queue < Stare, vector < Stare >, comp > Heap;

void Do();
void Print();

void Read()
{
  fin >> N >> M >> K >> tasks;

  int a, b, c;

  for( int i = 1; i <= M; ++i )
  {
    fin >> a >> b >> c;

    Ad[ a ].push_back( b );
    Cost[ a ].push_back( c );

    Ad[ b ].push_back( a );
    Cost[ b ].push_back( c );
  }

  for( int i = 1; i <= K; ++i )
  {
    fin >> a >> b >> c;

    Infra_time[ a ].push_back( b );
    Infra_pret[ a ].push_back( c );
  }

  for( int i = 1; i <= tasks; ++i )
  {
    fin >> place >> TAIM;

    Do();
    Print();
  }

  fin.close();
  fout.close();
}

void Do()
{
  for( int i = 0; i <= N; ++i )
    for( int j = 0; j <= TAIM + 2; ++j )
      mat[ i ][ j ] = -INF;

  temp.bani = 0;
  temp.moment = 0;
  temp.nod = 1;

  Heap.push( temp );

  mat[ 1 ][ 0 ] = 0;

  int n_curent;
  int b_curent;
  int t_curent;

  int w;

  while( !Heap.empty() )
  {
    n_curent = Heap.top().nod;
    t_curent = Heap.top().moment;
    b_curent = Heap.top().bani;

    Heap.pop();

   // fout << n_curent << ' ' << t_curent << ' ' << b_curent << '\n';

    for( int i = 0; i < Ad[ n_curent ].size(); ++i )
      if( t_curent + Cost[ n_curent ][ i ] <= TAIM ) /// DACA MAI ESTE TIMP DE MERS UNDEVA
     {
       w = Ad[ n_curent ][ i ];

       for( int j = 0; j < Infra_time[ w ].size(); ++j )
         if( t_curent + Cost[ n_curent ][ i ] <= Infra_time[ w ][ j ] ) /// DACA AJUNGE LA TIMP SA PRINDA INFRACTIUNEA
           if( mat[ w ][ Infra_time[ w ][ j ] ] < b_curent + Infra_pret[ w ][ j ] )
              {
                mat[ w ][ Infra_time[ w ][ j ] ] = b_curent + Infra_pret[ w ][ j ];

                temp.nod = w;
                temp.moment = Infra_time[ w ][ j ];
                temp.bani = mat[ w ][ Infra_time[ w ][ j ] ];

                Heap.push( temp );
              }

       if( t_curent + Cost[ n_curent ][ i ] < TAIM && mat[ w ][ t_curent + Cost[ n_curent ][ i ] ] < b_curent )
       {
         mat[ w ][ t_curent + Cost[ n_curent ][ i ] ] = b_curent;

         temp.nod = w;
         temp.moment = t_curent + Cost[ n_curent ][ i ];
         temp.bani = b_curent;

         Heap.push( temp );
       }
     }
  }
}

void Test()
{
  for( int i = 1; i <= N; ++i )
  {
    for( int j = 0; j <= TAIM; ++j )
      if( mat[i][j] == -INF ) fout << "* ";
      else fout << mat[i][j] << ' ';

    fout << '\n';
  }
}

void Print()
{
  bool ok = false;

  for( int i = TAIM; i >= 1; --i )
    if( mat[ place ][ i ] > -INF )
    {
      fout << mat[ place ][ i ] << '\n';
      ok = true;

      return;
    }

  if( ! ok ) fout << "-1" << '\n';
}

int main()
{
    Read();

    /// Test();

    return 0;
}