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 getX(int d, int v) {
  int l = 0;
  int r = d;
  int sol = -1;
  while (l <= r) {
    int x = (l + r) / 2;
    int y = d - x;
    if (2 * x + y <= v) {
      sol = x;
      l = x + 1;
    } else {
      r = x - 1;
    }
  }
  return sol;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > cars(n);
  for (int i = 0; i < n; i++) {
    cin >> cars[i].first >> cars[i].second;
  }
  vector<int> g(k + 2);
  g[0] = 0;
  g[k + 1] = s;
  for (int i = 1; i <= k; i++) {
    cin >> g[i];
  }
  sort(g.begin(), g.end());
  k++;
  int sol = -1;
  int l = 1, r = 1000000010;
  while (l <= r) {
    int mid = (l + r) / 2;
    int id = -1;
    for (int i = 0; i < n; i++) {
      if (cars[i].first <= mid) {
        if (id == -1 || cars[id].second < cars[i].second) {
          id = i;
        }
      }
    }
    bool ok = (id != -1);
    int time = 0;
    for (int i = 1; ok && i <= k; i++) {
      int x = getX(g[i] - g[i - 1], cars[id].second);
      ok &= x != -1;
      if (ok) {
        time += x + (g[i] - g[i - 1] - x) * 2;
        ok &= (time <= t);
      }
    }
    if (ok) {
      r = mid - 1;
      sol = mid;
    } else {
      l = mid + 1;
    }
  }
  cout << sol << '\n';
}
