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 int MAXN = 200010;
int n, k, s, t;
int gas[MAXN];
struct Node {
  int c, v;
  friend bool operator<(const Node &p, const Node &q) { return p.c < q.c; }
} P[MAXN];
int pre[MAXN];
int check(int o) {
  int tt = 0;
  for (int i = 1; i <= k; i++) {
    int x = gas[i] - gas[i - 1];
    if (o < x) return 2147483647;
    tt += max(x, 2 * x - (o - x));
  }
  return tt;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d%d", &P[i].c, &P[i].v);
  for (int i = 1; i <= k; i++) scanf("%d", &gas[i]);
  sort(gas + 1, gas + k + 1);
  gas[++k] = s;
  int l = 1, r = n;
  sort(P + 1, P + n + 1);
  for (int i = 1; i <= n; i++) pre[i] = max(pre[i - 1], P[i].v);
  while (l < r) {
    int mid = (l + r) >> 1;
    int o = pre[mid];
    int tt = check(o);
    if (tt <= t)
      r = mid;
    else
      l = mid + 1;
  }
  if (check(pre[l]) > t)
    puts("-1");
  else
    printf("%d\n", P[l].c);
  return 0;
}
