#include <bits/stdc++.h>
using namespace std;
const long long int inf = 1e15;
const long long int mod = 1000000007;
const int infInt = 1e9;
const double PI = acos(-1.00);
const double eps = 1e-6;
long long int nCars, nGas, len, Time;
pair<long long int, long long int> cars[200010];
long long int stations[200010];
long long int bb(long long int ini, long long int fin, long long int fuel) {
  long long int ans = -1;
  long long int dist = fin;
  while (ini <= fin) {
    long long int mid = (ini + fin) / 2;
    if (2LL * mid + (dist - mid) <= fuel) {
      ans = mid;
      ini = mid + 1;
    } else {
      fin = mid - 1;
    }
  }
  return ans;
}
bool can(long long int fuel) {
  long long int timeSpend = 0;
  long long int ant = 0;
  for (int i = 0; i < nGas; i++) {
    long long int dist = stations[i] - ant;
    ant = stations[i];
    if (2LL * dist <= fuel) {
      timeSpend += dist;
      continue;
    }
    if (dist > fuel) return false;
    long long int bestAcc = bb(0, dist, fuel);
    timeSpend += bestAcc + 2 * (dist - bestAcc);
  }
  return (timeSpend <= Time);
}
int main() {
  cin.sync_with_stdio(false);
  cin.tie(NULL);
  long long int maxi = -inf;
  cin >> nCars >> nGas >> len >> Time;
  for (int i = 0; i < nCars; i++) {
    cin >> cars[i].first >> cars[i].second;
    maxi = max(maxi, cars[i].second);
  }
  for (int i = 0; i < nGas; i++) {
    cin >> stations[i];
  }
  sort(stations, stations + nGas);
  stations[nGas++] = len;
  long long int ini = 0, fin = maxi;
  long long int bestFuel = -1;
  while (ini <= fin) {
    long long int mid = (ini + fin) / 2;
    if (can(mid)) {
      bestFuel = mid;
      fin = mid - 1;
    } else {
      ini = mid + 1;
    }
  }
  if (bestFuel == -1)
    cout << -1 << "\n";
  else {
    long long int best = inf;
    for (int i = 0; i < nCars; i++) {
      if (cars[i].second >= bestFuel) {
        best = min(best, cars[i].first);
      }
    }
    cout << best << "\n";
  }
}
