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;
struct car {
  long long c, v;
} a[200005];
long long b[200005];
vector<long long> vc;
int main() {
  int n, k;
  long long s, t;
  scanf("%d%d%lld%lld", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) {
    long long c, v;
    scanf("%lld%lld", &c, &v);
    a[i] = {c, v};
  }
  for (int i = 1; i <= k; i++) scanf("%lld", b + i);
  b[k + 1] = s;
  sort(b + 1, b + k + 1);
  long long accels = max(s + s - t, 0LL);
  if (accels > s) {
    printf("-1");
    return 0;
  }
  for (int i = 0; i <= k; i++) {
    vc.push_back(b[i + 1] - b[i]);
  }
  sort(vc.begin(), vc.end());
  long long p = vc.back(), q = s + 1;
  while (p <= q) {
    long long mid = (p + q) / 2, boosts = 0;
    bool valid = true;
    for (long long x : vc) {
      boosts += min(mid - x, x);
    }
    if (boosts < accels)
      p = mid + 1;
    else
      q = mid - 1;
  }
  long long fuels = p;
  if (q >= s + 1) {
    printf("-1");
    return 0;
  }
  long long ans = (1LL << 62);
  for (int i = 0; i < n; i++) {
    if (a[i].v >= fuels) ans = min(ans, a[i].c);
  }
  if (ans == (1LL << 62))
    printf("-1");
  else
    printf("%lld", ans);
  return 0;
}
