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 n, k, s, t, tmp;
pair<int, int> Car[200200];
set<int> gas;
bool Try(int m) {
  int pre = 0;
  int T = 0;
  for (auto x : gas) {
    int dist = x - pre;
    if (dist > m)
      return false;
    else {
      if (m >= 2 * dist)
        T += dist;
      else
        T += 2 * dist - (m - dist);
      pre = x;
    }
  }
  return T <= t;
}
int bin_srch(int L, int R) {
  if (L + 1 == R) {
    if (Try(L))
      return L;
    else
      return R;
  }
  int mid = L + R >> 1;
  if (Try(mid))
    return bin_srch(L, mid);
  else
    return bin_srch(mid, R);
}
int main() {
  scanf("%i%i", &n, &k), scanf("%i%i", &s, &t);
  for (int i = 0; i < n; i++) scanf("%i%i", &Car[i].first, &Car[i].second);
  for (int i = 0; i < k; i++) scanf("%i", &tmp), gas.insert(tmp);
  gas.insert(s);
  int min_cap = bin_srch(1, 1e9);
  int ans = 2e9;
  for (int i = 0; i < n; i++)
    if (Car[i].second >= min_cap) ans = min(ans, Car[i].first);
  printf("%i", ans == 2e9 ? -1 : ans);
  putc('\n', stdout);
}
