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;
int n, k, s, t;
vector<int> g;
vector<pair<int, int> > cars;
bool CanReach(int capacity) {
  int time_left = t;
  for (int i = 0; i < k - 1; i++) {
    int distance = g[i + 1] - g[i];
    if (distance > capacity) return false;
    int accel = capacity - distance;
    if (accel > distance) accel = distance;
    int time = distance * 2 - accel;
    time_left -= time;
    if (time_left < 0) return false;
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  scanf("%d%d%d%d", &n, &k, &s, &t);
  g = vector<int>(k);
  cars = vector<pair<int, int> >(n);
  for (int i = 0; i < n; i++) scanf("%d%d", &cars[i].second, &cars[i].first);
  for (int i = 0; i < k; i++) scanf("%d", &g[i]);
  g.push_back(0);
  g.push_back(s);
  k += 2;
  sort(g.begin(), g.end());
  sort(cars.begin(), cars.end());
  for (int i = cars.size() - 1 - 1; i >= 0; i--)
    if (cars[i].second > cars[i + 1].second)
      cars[i].second = cars[i + 1].second;
  int l = 0, h = cars.size() - 1;
  while (l <= h) {
    int mid = (l + h) >> 1;
    if (CanReach(cars[mid].first))
      h = mid - 1;
    else
      l = mid + 1;
  }
  if (l == n)
    cout << -1 << endl;
  else
    cout << cars[l].second << endl;
  return 0;
}
