#include <bits/stdc++.h>
using namespace std;
long long n, k, s, t, a[300000];
struct car {
  long long c, v;
};
car z[300000];
bool f(long long i) {
  long long tek = 0, buck = z[i].v, ans = 0;
  for (long long j = 0; j < k; j++) {
    long long _time = 0, litrs = buck;
    if ((a[j] - tek) * 2 > litrs) {
      long long delta = (a[j] - tek) * 2;
      long long q1 = (a[j] - tek);
      long long q2 = buck - q1;
      if (q2 < 0) return false;
      delta -= q2;
      _time = delta;
    } else
      _time = a[j] - tek;
    ans += _time;
    tek = a[j];
  }
  return ans <= t;
}
bool cmp(car a, car b) {
  if (a.v != b.v) return a.v < b.v;
  return a.c < b.c;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  for (long long i = 0; i < n; i++) cin >> z[i].c >> z[i].v;
  for (long long i = 0; i < k; i++) cin >> a[i];
  sort(a, a + k);
  k++;
  a[k - 1] = s;
  sort(z, z + n, cmp);
  long long l = 0, r = n;
  while (l < r - 1) {
    long long m = (l + r) / 2;
    if (f(m))
      r = m;
    else
      l = m;
  }
  long long mn = 999999999999999, mn1 = 999999999999;
  if (f(l)) mn = z[l].v;
  if (f(r)) mn = min(mn, z[r].v);
  if (mn == 999999999999999) {
    cout << -1;
    return 0;
  }
  for (long long i = 0; i < n; i++) {
    if (z[i].v >= mn) {
      mn1 = min(z[i].c, mn1);
    }
  }
  cout << mn1;
}
