#include <bits/stdc++.h>
using namespace std;
const int maxn = 200005;
int n, k, s, t, flag = 0;
struct node {
  int c, v;
  node(int c = 0, int v = 0) : c(c), v(v) {}
  bool operator<(const node &a) const { return v < a.v; }
};
node car[maxn];
int ki[maxn], del[maxn];
void init() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; ++i) {
    int c, v;
    scanf("%d%d", &c, &v);
    car[i] = node(c, v);
  }
  for (int i = 1; i <= k; ++i) scanf("%d", &ki[i]);
  sort(ki + 1, ki + k + 1);
  del[0] = ki[1];
  for (int i = 1; i <= k - 1; ++i) del[i] = ki[i + 1] - ki[i];
  del[k] = s - ki[k];
}
bool check(int nw) {
  int l = car[nw].v, tim = 0;
  for (int i = 0; i <= k; ++i) {
    if (2 * del[i] <= l)
      tim += del[i];
    else if (del[i] > l / 2 && del[i] <= l)
      tim += (3 * del[i] - l);
    else
      return 0;
  }
  if (tim <= t) {
    flag = 1;
    return 1;
  } else
    return 0;
}
int py = 0;
node ys[maxn];
int main() {
  init();
  sort(car + 1, car + n + 1);
  int l = 1, r = n;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (check(mid))
      r = mid - 1;
    else
      l = mid + 1;
  }
  int std = car[l].v;
  for (int i = 1; i <= n; ++i)
    if (car[i].v >= std) ys[++py] = car[i];
  if (!flag) {
    printf("-1");
    return 0;
  }
  int ans = 2147483647;
  for (int i = 1; i <= py; ++i) ans = min(ans, ys[i].c);
  printf("%d", ans);
  return 0;
}
