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 c[222222], v[222222], a[222222];
int main() {
  int n, k, s, t;
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) {
    scanf("%d %d", c + i, v + i);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", a + i);
  }
  sort(a, a + k);
  a[k] = s;
  for (int i = k; i >= 0; i--) {
    if (i) a[i] -= a[i - 1];
  }
  int st = 0, ed = s, mid;
  while (ed - st > 1) {
    mid = (st + ed) >> 1;
    long long T = 0;
    for (int i = 0; i <= k; i++) {
      if (a[i] > mid) {
        T = 0x3f3f3f3f;
        break;
      } else if (mid < 2 * a[i]) {
        T += (3LL * a[i] - mid);
      } else
        T += a[i];
    }
    if (T <= t)
      ed = mid;
    else
      st = mid;
  }
  int ans = 0x3f3f3f3f;
  for (int i = 0; i < n; i++) {
    if (v[i] >= ed) ans = min(ans, c[i]);
  }
  printf("%d\n", ans == 0x3f3f3f3f ? -1 : ans);
  return 0;
}
