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;
const long long MAXN = 1e5 + 10;
struct node {
  long long v, m;
} st[2 * MAXN];
long long vis[MAXN * 2], s, t, n, k, low, high;
bool calc(long long w) {
  long long ans = 0;
  for (int i = 1; i <= k; i++) {
    long long cut = vis[i] - vis[i - 1];
    if (w >= 2 * cut)
      ans += cut;
    else if (w < cut)
      return false;
    else
      ans += 3 * cut - w;
    if (ans > t) return false;
  }
  return true;
}
int main() {
  scanf("%I64d %I64d %I64d %I64d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%I64d %I64d", &st[i].m, &st[i].v);
  for (int i = 1; i <= k; i++) scanf("%I64d", &vis[i]);
  vis[0] = 0;
  vis[++k] = s;
  sort(vis, vis + k + 1);
  int ok = 1;
  low = 0;
  high = 2 * MAXN;
  while (low < high) {
    long long mid = (low + high) / 2;
    if (calc(mid))
      high = mid, ok = 0;
    else
      low = mid + 1;
  }
  long long ans = 2 * MAXN;
  for (int i = 1; i <= n; i++)
    if (st[i].v >= high && ans > st[i].m) ans = st[i].m;
  if (ans == MAXN * 2 || ok)
    printf("-1\n");
  else
    printf("%I64d\n", ans);
  return 0;
}
