#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
int g[MAXN];
int p[MAXN];
int c[MAXN];
int dis[MAXN];
int dis2[MAXN];
int ds[MAXN];
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", p + i, c + i);
  for (int i = 0; i < k; i++) scanf("%d", g + i);
  sort(g, g + k);
  for (int i = 0; i < k; i++) {
    dis[i] = g[i];
    if (i) dis[i] -= g[i - 1];
    dis2[i] = 2 * dis[i];
  }
  dis[k] = s - g[k - 1];
  dis2[k] = 2 * dis[k];
  sort(dis, dis + k + 1);
  sort(dis2, dis2 + k + 1);
  ds[0] = dis[0];
  for (int i = 1; i <= k; i++) ds[i] = dis[i] + ds[i - 1];
  int mn = 1000000005;
  for (int i = 0; i < n; i++) {
    if (c[i] < dis[k]) continue;
    long long save = 0;
    int ind = upper_bound(dis2, dis2 + k + 1, c[i]) - dis2;
    ind--;
    if (ind >= 0) save += ds[ind];
    int rem = k - ind;
    int rest = ds[k];
    if (ind >= 0) rest -= ds[ind];
    save += rem * 1ll * c[i] - rest;
    if (2 * s - save <= t) mn = min(mn, p[i]);
  }
  if (mn <= 1000000000)
    printf("%d\n", mn);
  else
    printf("-1\n");
}
