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 gs[200000], tr[(1 << 19) + 1];
map<int, int> cti, itc;
set<int> ccc;
int cc[200000], cv[200000], k;
void update(int c, int l, int r, int i, int v) {
  if (l == r) {
    if (v > tr[c]) tr[c] = v;
    return;
  }
  int t = (l + r) >> 1;
  if (i <= t)
    update(2 * c, l, t, i, v);
  else
    update(2 * c + 1, t + 1, r, i, v);
  tr[c] = max(tr[2 * c], tr[2 * c + 1]);
}
int query(int c, int cl, int cr, int ql, int qr) {
  if (cr < ql || cl > qr) return -1;
  if (cl >= ql && cr <= qr) return tr[c];
  int t = (cl + cr) >> 1;
  return max(query(2 * c, cl, t, ql, qr), query(2 * c + 1, t + 1, cr, ql, qr));
}
int solve(int v) {
  int pos = 0, t = 0;
  for (int i = 0; i < k; i++) {
    int dist = gs[i] - pos;
    if (v < dist) return 2e9;
    if (v >= dist * 2) {
      t += dist;
    } else {
      int x = v - dist;
      int y = dist * 2 - v;
      t += x + 2 * y;
    }
    pos = gs[i];
  }
  return t;
}
int main() {
  int n, s, t;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) {
    scanf("%d%d", cc + i, cv + i);
    ccc.insert(cc[i]);
  }
  int cn = 0;
  for (int i : ccc) {
    cti[i] = ++cn;
    itc[cn] = i;
  }
  for (int i = 0; i < n; i++) {
    update(1, 1, cn, cti[cc[i]], cv[i]);
  }
  for (int i = 0; i < k; i++) scanf("%d", gs + i);
  sort(gs, gs + k);
  gs[k++] = s;
  int l = 1, r = cn, ans = -1;
  while (r >= l) {
    int c = (l + r) >> 1;
    int ret = solve(query(1, 1, cn, 1, c));
    if (ret > t) {
      l = c + 1;
    } else {
      r = c - 1;
      ans = itc[c];
    }
  }
  printf("%d\n", ans);
}
