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 int a[200001], b[200001], s, t, n, k, i, j, v, h, d[200001],
    mini = 1000000000, ke[200001], de;
void check(long int a, long int b) {
  if (a > mini) return;
  long int c = 0, me = 0;
  for (int i = 1; i <= k + 1; i++) {
    if (b - (d[i] - d[i - 1]) >= 0)
      c = (d[i] - d[i - 1]) * 2 - (b - (d[i] - d[i - 1]));
    else {
      de++;
      ke[de] = -1;
      return;
    }
    if (c < d[i] - d[i - 1]) c = d[i] - d[i - 1];
    me += c;
  }
  if (me <= t) {
    if (a < mini) mini = a;
    de++;
    ke[de] = a;
  } else {
    de++;
    ke[de] = -1;
  }
}
int main() {
  cin >> n >> k >> s >> t;
  for (i = 1; i <= n; i++) cin >> a[i] >> b[i];
  for (i = 1; i <= k; i++) scanf("%d", &d[i]);
  sort(d + 1, d + k + 1);
  d[k + 1] = s;
  for (i = 1; i <= n; i++) check(a[i], b[i]);
  if (mini != 1000000000)
    cout << mini;
  else
    cout << -1;
}
