#include <bits/stdc++.h>
using namespace std;
const int maxn = 2 * 100000, maxk = 2 * 100000, inf = 0x3f3f3f3f;
int n, k, s, t;
struct car {
  int c, v;
} a[maxn + 10];
int d[maxk + 10];
int ans = inf;
void init() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d%d", &a[i].c, &a[i].v);
  for (int i = 1; i <= k; i++) scanf("%d", &d[i]);
  d[k + 1] = s;
}
bool cmp(car x, car y) { return x.v < y.v; }
bool check(int x) {
  double time = 0;
  for (int i = 1; i <= k + 1; i++) {
    double x1, x2;
    int tmp = d[i] - d[i - 1];
    x1 = (double)(max(0, 2 * tmp - a[x].v));
    x2 = 2 * (tmp - x1);
    if (x2 < 0) return false;
    time += 2 * x1 + x2 / 2;
    if (time > t) return false;
  }
  return true;
}
void solve() {
  sort(a + 1, a + 1 + n, cmp);
  sort(d + 1, d + 1 + k + 1);
  int l = 1, r = n;
  int mm = 0;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (check(mid))
      mm = mid, r = mid - 1;
    else
      l = mid + 1;
  }
  if (mm == 0)
    printf("-1");
  else {
    for (int i = mm; i <= n; i++) ans = min(ans, a[i].c);
    printf("%d\n", ans);
  }
}
int main() {
  init();
  solve();
  return 0;
}
