#include <bits/stdc++.h>
using namespace std;
using namespace placeholders;
const int MAXN = 2E5 + 10;
int n, K, S, T;
int v[MAXN], c[MAXN];
int a[MAXN];
int s[MAXN];
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", a + i);
  a[++K] = S;
  sort(a + 1, a + K + 1);
  for (int i = K; i > 0; --i) a[i] -= a[i - 1];
  sort(a + 1, a + K + 1);
  for (int i = 1; i <= K; ++i) s[i] = s[i - 1] + a[i];
  const int INF = 2E9;
  int ans = INF;
  for (int i = 1; i <= n; ++i) {
    if (a[K] > v[i]) continue;
    int r = lower_bound(a + 1, a + K + 1, v[i] + 1 >> 1) - a - 1;
    long long cost = s[r] + (s[K] - s[r]) * 3ll - (long long)(K - r) * v[i];
    if (cost <= T) ans = min(ans, c[i]);
  }
  printf("%d\n", ans == INF ? -1 : ans);
  return 0;
}
