#include <bits/stdc++.h>
using namespace std;
int greedy(int L, int F) {
  if (F < L) return -1;
  int l1 = min(L, F - L);
  int l2 = L - l1;
  return l1 + l2 * 2;
};
vector<int> g;
bool go(int T, int V) {
  int it = 0;
  int ret = 0;
  for (int x : g) {
    int q = greedy(x - it, V);
    if (q < 0) return false;
    ret += q;
    it = x;
  }
  return ret <= T;
}
int U[222222], V[222222];
int main() {
  int N, K, S, T;
  scanf("%d%d%d%d", &N, &K, &S, &T);
  for (int i = 0; i < N; i++) scanf("%d%d", U + i, V + i);
  for (int i = 0; i < K; i++) {
    int x;
    scanf("%d", &x);
    g.push_back(x);
  }
  sort(g.begin(), g.end());
  g.push_back(S);
  int lo = 1, hi = 1e9 + 1;
  while (lo < hi) {
    int mid = (lo + hi) / 2;
    if (go(T, mid))
      hi = mid;
    else
      lo = mid + 1;
  }
  int id = -1;
  for (int i = 0; i < N; i++) {
    if (V[i] >= lo) {
      if (id == -1 || U[i] < U[id]) id = i;
    }
  }
  if (id == -1)
    printf("-1");
  else
    printf("%d", U[id]);
}
