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 main() {
  long long n, k, s, t;
  scanf("%lld %lld %lld %lld", &n, &k, &s, &t);
  vector<pair<long long, long long> > cars;
  for (int i = 0; i < n; i++) {
    long long a, b;
    scanf("%lld %lld", &a, &b);
    cars.push_back(make_pair(b, a));
  }
  sort(cars.begin(), cars.end());
  long long sum = 0;
  long long maxi = -1;
  long long last = 0;
  vector<long long> gas;
  for (int i = 0; i < k; i++) {
    long long a;
    scanf("%lld", &a);
    gas.push_back(a);
  }
  sort(gas.begin(), gas.end());
  vector<long long> val;
  for (int i = 0; i < gas.size(); i++) {
    long long a = gas[i];
    if (maxi < a - last) {
      maxi = a - last;
    }
    val.push_back(a - last);
    sum += a - last;
    last = a;
  }
  sum += s - last;
  val.push_back(s - last);
  if (maxi < s - last) {
    maxi = s - last;
  }
  if (t < s) {
    printf("-1\n");
    return 0;
  }
  long long add = 0;
  if (t < 2 * s) {
    add = 2 * s - t;
  }
  long long min2 = maxi, max2 = 1000000000000000007, med = maxi;
  if (add)
    while (min2 < max2) {
      med = (min2 + max2) / 2;
      long long sum2 = 0;
      for (int i = 0; i < val.size(); i++) {
        sum2 += min(val[i], med - val[i]);
      }
      if (sum2 >= add) {
        max2 = med;
      }
      if (sum2 < add) {
        min2 = med + 1;
      }
    }
  long long ans = 1000000007;
  for (int i = 0; i < n; i++) {
    if (min2 <= cars[i].first) ans = min(ans, cars[i].second);
  }
  if (ans == 1000000007)
    printf("-1\n");
  else
    printf("%lld\n", ans);
  return 0;
}
