#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
const int NN = 1e6 * 4 + 1;
const double INF = 1e9 + 7;
int n, k, s, t;
int c[N], v[N];
int g[N];
int mn = INF;
bool f(int x) {
  int cnt = 0;
  g[k + 1] = s;
  for (int i = 1; i <= k + 1; i++) {
    int dist = g[i] - g[i - 1];
    if (dist > x) {
      return false;
    }
    cnt += min(dist, x - dist);
    cnt += (dist - min(dist, x - dist)) * 2;
  }
  if (cnt > t) {
    return false;
  }
  return true;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) {
    scanf("%d%d", &c[i], &v[i]);
  }
  for (int i = 1; i <= k; i++) {
    scanf("%d", &g[i]);
  }
  sort(g + 1, g + 1 + k);
  int l = 1;
  int r = int(2e9);
  while (r - l > 1) {
    int mid = (l + r) / 2;
    if (f(mid)) {
      r = mid;
    } else {
      l = mid;
    }
  }
  if (f(l)) {
    for (int i = 1; i <= n; i++) {
      if (v[i] >= l) {
        mn = min(mn, c[i]);
      }
    }
  }
  if (f(r)) {
    for (int i = 1; i <= n; i++) {
      if (v[i] >= r) {
        mn = min(mn, c[i]);
      }
    }
  }
  if (mn == INF) {
    cout << -1;
  } else {
    cout << mn;
  }
  return 0;
}
