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 information {
  long long c;
  long long v;
} car[200000], tempcar[200000];
long long n;
long long k;
long long s;
long long t;
long long tol = 0;
long long l[200000];
long long lt[200000];
long long temp[200000];
long long ltmax;
long long minprice;
int flag = 0;
void merge(long long l[], long long temp[], int start, int mid, int end) {
  int i, j, k;
  i = start;
  j = mid + 1;
  k = start;
  while (i != mid + 1 && j != end + 1) {
    if (l[i] > l[j]) {
      temp[k] = l[j];
      k++;
      j++;
    } else {
      temp[k] = l[i];
      k++;
      i++;
    }
  }
  while (i != mid + 1) {
    temp[k] = l[i];
    k++;
    i++;
  }
  while (j != end + 1) {
    temp[k] = l[j];
    k++;
    j++;
  }
  for (i = start; i <= end; i++) {
    l[i] = temp[i];
  }
}
void mergesort(long long l[], long long temp[], int start, int end) {
  int mid;
  if (start < end) {
    mid = (start + end) / 2;
    mergesort(l, temp, start, mid);
    mergesort(l, temp, mid + 1, end);
    merge(l, temp, start, mid, end);
  }
}
void mergecar(struct information car[200000],
              struct information tempcar[200000], int start, int mid, int end) {
  int i, j, k;
  i = start;
  j = mid + 1;
  k = start;
  while (i != mid + 1 && j != end + 1) {
    if (car[i].v > car[j].v) {
      tempcar[k] = car[j];
      k++;
      j++;
    } else {
      tempcar[k] = car[i];
      k++;
      i++;
    }
  }
  while (i != mid + 1) {
    tempcar[k] = car[i];
    k++;
    i++;
  }
  while (j != end + 1) {
    tempcar[k] = car[j];
    k++;
    j++;
  }
  for (i = start; i <= end; i++) {
    car[i] = tempcar[i];
  }
}
void mergesortcar(struct information car[200000],
                  struct information tempcar[200000], int start, int end) {
  int mid;
  if (start < end) {
    mid = (start + end) / 2;
    mergesortcar(car, tempcar, start, mid);
    mergesortcar(car, tempcar, mid + 1, end);
    mergecar(car, tempcar, start, mid, end);
  }
}
int check(long long v) {
  long long i;
  if (v < ltmax) return 0;
  for (i = 0; i <= k; i++) {
    if (v > 2 * lt[i])
      tol = tol + lt[i];
    else
      tol = tol + 3 * lt[i] - v;
    if (tol > t) return 0;
  }
  flag = 1;
  return 1;
}
int main() {
  long long i, j;
  scanf("%lld%lld%lld%lld", &n, &k, &s, &t);
  for (i = 0; i < n; i++) {
    scanf("%lld%lld", &car[i].c, &car[i].v);
  }
  for (i = 0; i < k; i++) {
    scanf("%lld", &l[i]);
  }
  mergesort(l, temp, 0, k - 1);
  l[k] = s;
  for (i = k; i > 0; i--) {
    lt[i] = l[i] - l[i - 1];
  }
  lt[0] = l[0];
  ltmax = l[0];
  for (i = 0; i <= k; i++) {
    if (ltmax < lt[i]) ltmax = lt[i];
  }
  mergesortcar(car, tempcar, 0, n - 1);
  long long left, right, mid;
  left = 0;
  right = n;
  flag = 0;
  while (left < right) {
    tol = 0;
    mid = (left + right) / 2;
    if (check(car[mid].v) == 1)
      right = mid;
    else
      left = mid + 1;
  }
  if (flag == 0)
    printf("%d", -1);
  else {
    minprice = car[left].c;
    for (i = left; i < n; i++) {
      if (car[i].c < minprice) minprice = car[i].c;
    }
    printf("%lld", minprice);
  }
  return 0;
}
