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;
pair<int, int> ar[200010];
long long br[200010];
long long n, k;
bool chk(long long cap, long long x) {
  long long tmp;
  for (int i = k; i >= 0; i--) {
    if (br[i] > cap) return false;
    tmp = 2 * br[i] - cap;
    if (tmp > 0) {
      x -= tmp;
      if (x < 0) {
        return false;
      }
    } else
      break;
  }
  return true;
}
int bin(int l, int r, long long x) {
  if (l == r) return l;
  int mid = (l + r) / 2;
  if (chk(ar[mid].first, x))
    return bin(l, mid, x);
  else
    return bin(mid + 1, r, x);
}
void solve() {
  long long s, t;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    scanf("%d", &ar[i].second);
    ;
    scanf("%d", &ar[i].first);
    ;
  }
  sort(ar, ar + n);
  for (int i = n - 2; i >= 0; i--) {
    ar[i].second = min(ar[i].second, ar[i + 1].second);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", &br[i]);
    ;
  }
  sort(br, br + k);
  br[k] = s - br[k - 1];
  for (int i = k - 1; i > 0; i--) {
    br[i] -= br[i - 1];
  }
  sort(br, br + k + 1);
  long long x = t - s;
  if (x < 0) {
    printf("-1\n");
    return;
  }
  if (!chk(ar[n - 1].first, x)) {
    printf("-1\n");
    return;
  }
  long long ans = bin(0, n - 1, x);
  printf("%d\n", ar[ans].second);
}
int main() {
  int t = 1;
  for (int i = 1; i <= t; i++) {
    solve();
  }
}
