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 = 200000;
const int MAXV = 200000;
int g[MAXV + 10], n, s, k, t;
struct Car {
  int v, c;
  bool operator<(const Car& rhs) const { return v < rhs.v; }
} cars[MAXN + 10];
bool check(int val) {
  double t_cnt = 0;
  for (int i = 0; i <= k; i++) {
    if (g[i + 1] - g[i] > val) return false;
    t_cnt += 2.0 * (g[i + 1] - g[i]);
    int oth = val - g[i + 1] + g[i];
    if (oth > g[i + 1] - g[i])
      t_cnt -= 1.0 * (g[i + 1] - g[i]);
    else
      t_cnt -= 1.0 * oth;
  }
  return t_cnt <= t;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d%d", &cars[i].c, &cars[i].v);
  sort(cars + 1, cars + 1 + n);
  for (int i = 1; i <= k; i++) scanf("%d", &g[i]);
  sort(g + 1, g + 1 + k);
  g[k + 1] = s;
  int L = 0, R = cars[n].v, ans = -1;
  while (L <= R) {
    int mid = (L + R) >> 1;
    if (check(mid)) {
      ans = mid;
      R = mid - 1;
    } else
      L = mid + 1;
  }
  if (ans == -1) {
    printf("-1\n");
    return 0;
  }
  int op = 0x3f3f3f3f;
  for (int i = n; i >= 1; i--) {
    if (cars[i].v < ans) break;
    op = min(op, cars[i].c);
  }
  printf("%d\n", op);
  return 0;
}
