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 bin_search(long a[], long f, long l, long val) {
  long first = f, last = l, mid;
  while (last >= first) {
    mid = (last + first) / 2;
    if (val == a[mid])
      return mid;
    else if (val > a[mid])
      first = mid + 1;
    else if (val < a[mid])
      last = mid;
  }
  return -1;
}
bool can(long n, long k, long s, long t, long g[]) {
  long pos = 0, dis, time = 0;
  for (int i = 0; i <= k; i++) {
    dis = g[i] - pos;
    if (n < dis) return 0;
    time += (n >= 2 * dis ? dis : 3 * dis - n);
    if (time > t) return 0;
    pos = g[i];
  }
  return 1;
}
void sort_arr(long c[], long v[], long f, long l) {
  long mid = f;
  if (l - f == 1 && v[f] > v[l]) {
    swap(v[f], v[l]);
    swap(c[f], c[l]);
  } else if (l - f > 1) {
    for (int i = mid + 1; i <= l; i++) {
      if (v[i] <= v[mid]) {
        swap(v[mid + 1], v[i]);
        swap(v[mid], v[mid + 1]);
        swap(c[mid + 1], c[i]);
        swap(c[mid], c[mid + 1]);
        mid++;
      }
    }
    sort_arr(c, v, f, mid - 1);
    sort_arr(c, v, mid + 1, l);
  }
}
int bin_c(long f, long l, long k, long s, long t, long g[]) {
  int first = f, last = l, mid, mn = LONG_MAX;
  while (last >= first) {
    mid = (last + first) / 2;
    if (can(mid, k, s, t, g)) {
      mn = min(mn, mid);
      last = mid - 1;
    } else
      first = mid + 1;
  }
  return (mn == LONG_MAX ? -1 : mn);
}
int main() {
  long n, k, s, t, price = LONG_MAX;
  cin >> n >> k >> s >> t;
  long c[n], v[n];
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  long g[k + 1];
  for (int i = 0; i < k; i++) cin >> g[i];
  g[k] = s;
  sort(g, g + k);
  long low = bin_c(0, 500, k, s, t, g);
  sort_arr(c, v, 0, n - 1);
  for (int i = 0; i < n; i++) {
    if (v[i] >= low) {
      price = min(price, c[i]);
    }
  }
  if (price < LONG_MAX)
    cout << price;
  else
    cout << -1;
  return 0;
}
