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, m, x, y, z, k, w, need, ans, tmp, s, t;
int A[200005], B[200005], G[200005];
int high, low, mid;
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = (0); i < (n); i++) scanf("%d %d", &A[i], &B[i]);
  for (int i = (0); i < (k); i++) scanf("%d", &G[i]);
  sort(G, G + k);
  high = 1000000001;
  low = 0;
  need = s * 2 - t;
  if (need <= 0) {
    ans = A[0];
    for (int i = (0); i < (n); i++) ans = min(ans, A[i]);
    printf("%d\n", ans);
    return 0;
  }
  G[k] = s;
  while (high - low > 1) {
    mid = (high + low) / 2;
    x = 0;
    y = 1;
    tmp = 0;
    for (int i = (0); i < (k + 1); i++) {
      if ((G[i] - x) * 2 <= mid)
        tmp += G[i] - x;
      else if ((G[i] - x) > mid) {
        y = 0;
        break;
      } else
        tmp += (mid - (G[i] - x));
      x = G[i];
    }
    if (y == 0)
      low = mid;
    else if (tmp >= need)
      high = mid;
    else
      low = mid;
  }
  ans = 1234567890;
  for (int i = (0); i < (n); i++)
    if (B[i] >= high) ans = min(ans, A[i]);
  if (ans == 1234567890) ans = -1;
  printf("%d\n", ans);
  return 0;
}
