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>
struct car {
  int price;
  int cpct;
};
int cmp_point(const void* a, const void* b) { return *(int*)a - *(int*)b; }
int cmp_car(const void* a, const void* b) {
  return ((struct car*)a)->price - ((struct car*)b)->price;
}
int main() {
  int n, k, s, t, is_ok, d, choice = 0;
  int i, count, time;
  scanf("%d %d %d %d", &n, &k, &s, &t);
  struct car group[n];
  int point[k];
  for (i = 0; i < n; ++i) scanf("%d %d", &group[i].price, &group[i].cpct);
  for (i = 0; i < k; ++i) scanf("%d", &point[i]);
  point[k] = 0;
  point[k + 1] = s;
  qsort(group, n, sizeof(struct car), cmp_car);
  qsort(point, k + 2, sizeof(int), cmp_point);
  for (i = 0; i < n && !choice; ++i) {
    for (count = 0, is_ok = 1, time = 0; count < k && is_ok; ++count) {
      d = point[count + 1] - point[count];
      if (d > group[i].cpct)
        is_ok = 0;
      else {
        time += 3 * d - group[i].cpct;
        if (time > t) is_ok = 0;
      }
    }
    if (is_ok) choice = i;
  }
  if (choice)
    printf("%d", group[choice].price);
  else
    printf("-1");
}
