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 a[1000009] = {};
int b[1000009] = {};
int c[1000009] = {};
int Max, t, k;
int check(int n) {
  if (n < Max) {
    return 0;
  }
  int sum = 0;
  int f = c[0];
  for (int i = 0; i < k + 1; i++) {
    if (i != 0) f = c[i] - c[i - 1];
    sum += max(f, (f * 2 - (n - f)));
    if (sum > t) {
      return 0;
    }
  }
  return 1;
}
int half() {
  int L = 0, R = 1e9, ans = 0;
  while (L <= R) {
    int mid = (L + R) / 2;
    int k = check(mid);
    if (k == 0) {
      L = mid + 1;
    } else {
      R = mid - 1;
      ans = mid;
    }
  }
  return ans;
}
int main() {
  int n, s, result = 0, tom;
  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", &c[i]);
  }
  c[k] = s;
  sort(c, c + k + 1);
  Max = c[0];
  for (int i = 1; i < k + 1; i++) {
    Max = max(Max, c[i] - c[i - 1]);
  }
  result = half();
  int flag = 1;
  for (int i = 0; i < n; i++) {
    if (result <= b[i]) {
      if (flag == 1) {
        tom = a[i];
        flag = 0;
      } else {
        tom = min(tom, a[i]);
      }
    }
  }
  if (flag == 1) {
    printf("-1\n");
  } else {
    printf("%d\n", tom);
  }
}
