#include <bits/stdc++.h>
using namespace std;
const int maxv = 1000000000;
const int maxn = 200000 + 10;
const int maxk = 200000 + 10;
struct Car {
  int c, v;
  bool operator<(const Car &x) const { return c < x.c; }
};
Car cars[maxn];
int p[maxk], d[maxk];
bool ok(int v, int k, int t) {
  int r = 0;
  for (int i = k; i >= 0; i--) {
    if (d[i] > v) return false;
    if (v / 2 >= d[i])
      r += d[i];
    else
      r += d[i] + d[i] - v + d[i];
  }
  return r <= t;
}
int main() {
  int n, k, s, t;
  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);
  p[0] = 0;
  for (int i = 1; i <= k; i++) scanf("%d", &p[i]);
  sort(p + 1, p + 1 + k);
  p[k + 1] = s;
  for (int i = 0; i <= k; i++) d[i] = p[i + 1] - p[i];
  sort(d, d + k + 1);
  int L = 1, R = maxv, M, c = maxv + 1;
  while (L <= R) {
    M = (L + R) / 2;
    if (ok(M, k, t)) {
      c = M;
      R = M - 1;
    } else
      L = M + 1;
  }
  for (int i = 1; i <= n; i++) {
    if (cars[i].v >= c) {
      printf("%d\n", cars[i].c);
      return 0;
    }
  }
  puts("-1");
  return 0;
}
