#include <bits/stdc++.h>
using namespace std;
const int OO = 2e9;
const int MOD = 1e9 + 7;
const double Pi = 3.141592653589793;
const int N = 3e5 + 5;
long long c[N], v[N], g[N], a[N], n, k, s, t, m = 0, mx = 0, mn = -1, res = OO;
bool check(long long cap) {
  long long time = 0;
  for (int i = (int)1; i <= (int)m; i++) {
    if (a[i] > cap) return false;
    long long y = max(0LL, min(a[i], cap - a[i])), x = a[i] - y;
    time += 2LL * x + y;
  }
  return (time <= t);
}
int main() {
  cin >> n >> k >> s >> t;
  if (s > t) {
    cout << -1;
    return 0;
  }
  for (int i = (int)1; i <= (int)n; i++) scanf("%i%i", &v[i], &c[i]);
  for (int i = (int)1; i <= (int)k; i++) scanf("%i", &g[i]);
  g[++k] = s;
  g[++k] = 0;
  sort(g + 1, g + k + 1);
  for (int i = (int)2; i <= (int)k; i++)
    a[++m] = g[i] - g[i - 1], mx = max(mx, a[m]);
  long long l = mx, r = s * 2, mid;
  while (l <= r) {
    mid = (l + r) >> 1;
    if (check(mid))
      mn = mid, r = mid - 1;
    else
      l = mid + 1;
  }
  for (int i = (int)1; i <= (int)n; i++)
    if (c[i] >= mn) res = min(res, v[i]);
  if (res == OO)
    cout << -1;
  else
    cout << res;
}
