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;
int c[200005], v[200005], g[200005];
bool C(int vol) {
  int tt = 0;
  for (int i = 1; i <= k + 1; i++) {
    if (vol < g[i] - g[i - 1])
      return false;
    else if (vol >= 2 * (g[i] - g[i - 1]))
      tt += g[i] - g[i - 1];
    else {
      int dis = (g[i] - g[i - 1]) * 2 - vol;
      tt += g[i] - g[i - 1] + dis;
    }
  }
  return tt <= 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 + 1 + k);
  g[0] = 0;
  g[k + 1] = s;
  int l = 1, r = 1000000000;
  while (r - l > 1) {
    int mid = (l + r) / 2;
    if (C(mid))
      r = mid;
    else
      l = mid;
  }
  int ans = 1000000000 + 1;
  for (int i = 1; i <= n; i++)
    if (v[i] >= r) ans = min(ans, c[i]);
  if (ans == 1000000000 + 1)
    puts("-1");
  else
    printf("%d\n", ans);
  return 0;
}
