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;
const int N = 2 * 100009;
const int oo = 1000;
int n, k, s, t, ans, res, need;
int c[N], v[N], w[N];
bool check(int x) {
  int redun = 0;
  long long sum = 0;
  v[k + 1] = s;
  for (int i = 1; i <= k + 1; i++) {
    int len = v[i] - v[i - 1];
    if (len > x) return 0;
    redun = min(len, x - len);
    sum += redun;
  }
  return sum >= need;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d %d", &c[i], &w[i]);
  for (int i = 1; i <= n; i++) scanf("%d", &v[i]);
  sort(v + 1, v + k + 1);
  need = s * 2 - t;
  int left = 0;
  int right = s * 2;
  while (left <= right) {
    int mid = (left + right) >> 1;
    if (check(mid)) {
      ans = mid;
      right = mid - 1;
    } else
      left = mid + 1;
  }
  res = -1;
  for (int i = 1; i <= n; i++)
    if (w[i] >= ans)
      if (c[i] < res || res == -1) res = c[i];
  printf("%d", res);
}
