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;
const int N = 200011;
int c[N], v[N], g[N];
bool check(int tot) {
  for (int i = 1; i <= k; i++)
    if (g[i] - g[i - 1] > tot) return false;
  double ans = 0, tem, a, b;
  for (int i = 1; i <= k; i++) {
    if ((g[i] - g[i - 1]) * 2 <= tot)
      tem = g[i] - g[i - 1];
    else {
      b = tot - (g[i] - g[i - 1]);
      a = g[i] - g[i - 1] - b;
      tem = 2 * a + b;
    }
    ans += tem;
  }
  return (ans <= (double)t);
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d%d", &c[i], &v[i]);
  for (int i = 1; i <= k; i++) scanf("%d", &g[i]);
  sort(g + 1, g + k + 1);
  g[0] = 0;
  g[++k] = s;
  int l, r;
  l = 0;
  r = 1000000000;
  int mid;
  while (l + 1 < r) {
    mid = ((long long)l + r) / 2;
    if (check(mid) == true)
      r = mid;
    else
      l = mid;
  }
  int mx = 2000000000;
  for (int i = 1; i <= n; i++)
    if (v[i] >= r) mx = min(mx, c[i]);
  if (mx == 2000000000) mx = -1;
  printf("%d", mx);
}
