#include <bits/stdc++.h>
using namespace std;
inline int setBit(int N, int pos) { return N = N | (1 << pos); }
inline int resetBit(int N, int pos) { return N = N & ~(1 << pos); }
inline bool checkBit(int N, int pos) { return (bool)(N & (1 << pos)); }
int n, k;
long long s, T, P[200000 + 10];
pair<long long, long long> A[200000 + 10];
bool cmp(pair<long long, long long> a, pair<long long, long long> b) {
  return a.second < b.second;
}
bool ok(long long c) {
  long long ret = 0;
  for (int i = 1; i <= k + 1; i++) {
    long long x = P[i] - P[i - 1];
    if (x > c) return false;
    if (c / 2 >= x)
      ret += x;
    else {
      ret += (c - x) + 2 * (2 * x - c);
    }
  }
  return ret <= T;
}
int main() {
  int i, j, cs;
  scanf("%d %d", &n, &k);
  scanf("%lld %lld", &s, &T);
  for (i = 1; i <= n; i++) scanf("%lld %lld", &A[i].first, &A[i].second);
  for (i = 1; i <= k; i++) scanf("%lld", &P[i]);
  sort(A + 1, A + n + 1, cmp);
  sort(P + 1, P + k + 1);
  P[k + 1] = s;
  int lo = 1, hi = n, mid;
  while (lo < hi) {
    mid = (lo + hi) / 2;
    if (ok(A[mid].second))
      hi = mid;
    else
      lo = mid + 1;
  }
  if (!ok(A[lo].second))
    printf("-1\n");
  else {
    long long ret = A[hi].first;
    for (int i = hi; i <= n; i++) ret = min(A[i].first, ret);
    printf("%lld\n", ret);
  }
  return 0;
}
