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, s, t, pos[200005];
struct thing {
  int c, v;
  friend bool operator<(thing a, thing b) { return a.c > b.c; }
} car[200005];
bool check(int num) {
  int vol = car[num].v;
  int time = 0, Pos = 0;
  for (int i = 1; i <= k; i++) {
    if (pos[i] - Pos > vol) return false;
    if (2 * (pos[i] - Pos) <= vol)
      time += pos[i] - Pos;
    else
      time += vol - (pos[i] - Pos) + 2 * (2 * (pos[i] - Pos) - vol);
    Pos = pos[i];
  }
  if (time > t) return false;
  return true;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d%d", &car[i].c, &car[i].v);
  for (int i = 1; i <= k; i++) scanf("%d", &pos[i]);
  sort(pos + 1, pos + 1 + k);
  pos[++k] = s;
  sort(car + 1, car + 1 + n);
  vector<thing> st;
  for (int i = 1; i <= n; i++) {
    while (!st.empty() && st[st.size() - 1].v <= car[i].v)
      st.erase(st.end() - 1);
    st.push_back(car[i]);
  }
  n = st.size();
  for (int i = 1; i <= n; i++) car[i] = st[n - i];
  int l = 1, r = n;
  while (l != r) {
    int mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid + 1;
  }
  if (check(l))
    printf("%d\n", car[l].c);
  else
    printf("-1\n");
}
