1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

#include <bits/stdc++.h>
using namespace std;
long long n, k, s, t;
vector<int> stations;
bool checkFuel(int fuel) {
  int time = 0;
  int nextX;
  int x = 0;
  for (int i = 0; i < k && time < t; i++) {
    nextX = stations.at(i) - x;
    if (fuel < nextX) return false;
    if (stations.at(i) > s) {
      int temp = stations.at(i) - s;
      int boostTime = min(temp, fuel - temp);
      int normalTime = (temp - boostTime) * 2;
      time += boostTime + normalTime;
      if (time > t)
        return false;
      else
        return true;
    }
    x = nextX;
    int boostTime = min(nextX, fuel - nextX);
    int normalTime = (nextX - boostTime) * 2;
    time += boostTime + normalTime;
  }
  int temp = s - stations.at(k - 1);
  if (fuel < temp) return false;
  int boostTime = min(temp, fuel - temp);
  int normalTime = (temp - boostTime) * 2;
  time += boostTime + normalTime;
  if (time > t)
    return false;
  else
    return true;
}
int main() {
  cin >> n >> k >> s >> t;
  vector<pair<int, int>> cars(n);
  stations.resize(k);
  for (int i = 0; i < n; i++) cin >> cars.at(i).first >> cars.at(i).second;
  for (int i = 0; i < k; i++) cin >> stations.at(i);
  sort(stations.begin(), stations.end());
  int minPrice = INT_MAX;
  for (int i = 0; i < n; i++) {
    if (checkFuel(cars.at(i).second) && cars.at(i).first < minPrice)
      minPrice = cars.at(i).first;
  }
  if (minPrice == INT_MAX)
    cout << -1;
  else
    cout << minPrice;
  return 0;
}
