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 long long mod = 1000000007;
const long long inf = mod * mod;
pair<int, int> p[210000];
int f[210000];
int g[210000];
int main() {
  int a, b, c, d;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int ret = mod;
  for (int i = 0; i < a; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    p[i] = make_pair(y, x);
  }
  std::sort(p, p + a);
  for (int i = 0; i < b; i++) scanf("%d", f + i);
  f[b] = c;
  std::sort(f, f + b + 2);
  for (int i = 0; i < b + 1; i++) {
    g[i] = f[i + 1] - f[i];
  }
  std::sort(g, g + b + 1);
  b++;
  int at = 0;
  long long tn = 0;
  long long al = 0;
  for (int i = 0; i < b; i++) tn += g[i];
  tn *= 3;
  for (int i = 0; i < a; i++) {
    if (g[b - 1] > p[i].first) continue;
    while (at < b && g[at] * 2 <= p[i].first) {
      tn -= 3LL * g[at];
      al += g[at];
      at++;
    }
    long long cost = al + tn - (long long)(b - at) * p[i].first;
    if (cost <= d) ret = min(ret, p[i].second);
  }
  if (ret == mod) ret = -1;
  printf("%d\n", ret);
}
