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;
long long s, t;
pair<long long, long long> u[200007];
long long a[200007];
bool f(long long val) {
  int i;
  long long cur = 0;
  for (i = 0; i <= k; i++) {
    long long dist = a[i + 1] - a[i];
    if (val < dist) {
      return false;
    }
    long long h = (val - dist);
    if (h >= dist) {
      cur += dist;
    } else {
      cur += h;
      cur += 2 * (dist - h);
    }
    if (cur > t) {
      return false;
    }
  }
  return true;
}
void input() {
  scanf("%d%d", &n, &k);
  scanf("%I64d%I64d", &s, &t);
  int i;
  for (i = 1; i <= n; i++) {
    scanf("%I64d%I64d", &u[i].first, &u[i].second);
  }
  for (i = 1; i <= k; i++) {
    scanf("%I64d", &a[i]);
  }
  sort(a + 1, a + k + 1);
  a[0] = 0;
  a[k + 1] = s;
}
void solve() {
  if (t < s) {
    printf("-1\n");
    return;
  }
  long long l, r, mid;
  l = r = 1;
  int i;
  for (i = 1; i <= 12; i++) {
    r *= 10;
  }
  while ((r - l) > 3) {
    mid = (l + r) / 2;
    if (f(mid) == true) {
      r = mid;
    } else {
      l = mid;
    }
  }
  while (f(l) == false) {
    l++;
  }
  long long ans = -1;
  for (i = 1; i <= n; i++) {
    if (u[i].second < l) {
      continue;
    }
    if (ans == -1 || ans > u[i].first) {
      ans = u[i].first;
    }
  }
  printf("%I64d\n", ans);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  input();
  solve();
  return 0;
}
