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, i, dg, gg, r, c;
int benzinske[10 ^ 9 + 3];
bool provjeri(int r) {
  int t1 = 0, z;
  for (i = 1; i < k + 2; i++) {
    z = benzinske[i] - benzinske[i - 1];
    if (z > r) {
      return 0;
    } else if (r >= z and r < 2 * z) {
      t1 = t1 + 2 * z - (r - z);
    } else {
      t1 = t1 + z;
    }
  }
  if (t1 > t) {
    return 0;
  } else {
    return 1;
  }
}
int main() {
  cin >> n;
  cin >> k;
  cin >> s;
  cin >> t;
  int niz1[n], niz2[n];
  for (i = 0; i < n; i++) {
    cin >> niz1[i];
    cin >> niz2[i];
  }
  benzinske[0] = 0;
  benzinske[k + 1] = s;
  for (i = 1; i < k + 1; i++) {
    cin >> benzinske[i];
  }
  sort(benzinske, benzinske + k + 2);
  dg = 0;
  gg = 2 * s;
  while (dg != gg) {
    r = (dg + gg) / 2;
    if (provjeri(r) == 0) {
      dg = r + 1;
    } else {
      gg = r;
    }
  }
  c = 1000000;
  for (i = 0; i < n; i++) {
    if (niz2[i] >= gg and niz1[i] < c) {
      c = niz1[i];
    }
  }
  cout << c << endl;
  return 0;
}
