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, m, s, t, l, r, mid, ans;
int mincost;
int c[200005], v[200005], a[200005];
bool check(int x) {
  int pos = 0;
  int dqt = 0;
  for (int i = 1; i <= m; ++i) {
    int len = a[i] - pos;
    if (x < len) return false;
    int c1, c2 = x - len;
    c2 = min(c2, len);
    c1 = len - c2;
    dqt += 2 * c1 + c2;
    pos = a[i];
  }
  if (dqt <= t)
    return true;
  else
    return false;
}
int main() {
  scanf("%d%d%d%d", &n, &m, &s, &t);
  for (int i = 1; i <= n; ++i) scanf("%d%d", &c[i], &v[i]);
  for (int i = 1; i <= m; ++i) scanf("%d", &a[i]);
  ++m;
  a[m] = s;
  sort(a + 1, a + m + 1);
  l = 0;
  r = 1e9;
  ans = -1;
  while (l <= r) {
    mid = (l + r) / 2;
    if (check(mid)) {
      ans = mid;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  mincost = 2e9;
  for (int i = 1; i <= n; ++i)
    if (v[i] >= ans) mincost = min(mincost, c[i]);
  if (mincost == 2e9) mincost = -1;
  printf("%d\n", mincost);
  return 0;
}
