#include <bits/stdc++.h>
using namespace std;
int g[200000 + 10], n, s, k, t;
void Read(int& x) {
  char c;
  while (c = getchar(), c != EOF) {
    if (c >= '0' && c <= '9') {
      x = c - '0';
      while (c = getchar(), c >= '0' && c <= '9') x = x * 10 + c - '0';
      ungetc(c, stdin);
      return;
    }
  }
}
struct Car {
  int v, c;
  bool operator<(const Car& rhs) const { return v < rhs.v; }
} cars[200000 + 10];
bool check(int val) {
  double ret = 0;
  for (int i = 0; i <= k; i++) {
    if (g[i + 1] - g[i] > val) return false;
    ret += 2.0 * (g[i + 1] - g[i]);
    int oth = val - g[i + 1] + g[i];
    if (oth > g[i + 1] - g[i])
      ret -= 1.0 * (g[i + 1] - g[i]);
    else
      ret -= 1.0 * oth;
  }
  return ret <= t;
}
int main() {
  Read(n), Read(k), Read(s), Read(t);
  for (int i = 1; i <= n; i++) Read(cars[i].c), Read(cars[i].v);
  sort(cars + 1, cars + 1 + n);
  for (int i = 1; i <= k; i++) Read(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;
}
