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>
long long c[200010], v[200010], p[200010];
long long n, m, s, t;
bool ok(long long x) {
  long long ti = 0;
  for (long long k = 0; k <= m; k++) {
    long long di = p[k + 1] - p[k];
    if (x < di) return false;
    if (x >= 2 * di) {
      ti += di;
    } else {
      ti += (3 * di - x);
    }
  }
  if (ti <= t) return true;
  return false;
}
int main() {
  int k;
  scanf("%I64d%I64d%I64d%I64d", &n, &m, &s, &t);
  for (k = 1; k <= n; k++) scanf("%I64d%I64d", &c[k], &v[k]);
  for (k = 1; k <= m; k++) scanf("%I64d", &p[k]);
  std::sort(p + 1, p + m + 1);
  p[0] = 0;
  p[m + 1] = s;
  long long ans = 2e9;
  long long L = 0, R = 2e9, M, max = 0;
  for (k = 0; k <= m; k++) {
    if (max < p[k + 1] - p[k]) max = p[k + 1] - p[k];
  }
  L = max;
  while (L + 3 < R) {
    M = (L + R) / 2;
    if (ok(M))
      R = M;
    else
      L = M;
  }
  puts("QQ");
  long long qq = -1;
  for (k = L; k <= R; k++) {
    if (ok(k)) {
      qq = k;
      break;
    }
  }
  ans = 2e9;
  if (qq == -1) {
    puts("-1");
    return 0;
  }
  for (k = 1; k <= n; k++) {
    if (v[k] >= qq)
      if (c[k] < ans) ans = c[k];
  }
  if (ans != 2e9)
    printf("%I64d", ans);
  else
    puts("-1");
}
