#include <bits/stdc++.h>
using namespace std;
const unsigned long long max_ull = 18446744073709551615ull;
const long long max_ll = 9223372036854775807ll;
unsigned long long nextInt() {
  unsigned long long sum = 0;
  char a;
  while (true) {
    a = getchar();
    if (a < '0' || a > '9') return sum;
    sum = sum * 10 + (unsigned long long)(a - '0');
  }
}
vector<pair<long long, long long> > g, g2;
long long n, k, s, t, ans = -1, mxb = 0, gas[200050], l, r, m;
int main() {
  n = nextInt();
  k = nextInt();
  s = nextInt();
  t = nextInt();
  g.resize(n);
  for (int i = 0; i < n; i++) {
    g[i].first = nextInt();
    g[i].second = nextInt();
  }
  for (int i = 0; i < k; i++) gas[i] = nextInt();
  gas[k] = s;
  sort(gas, gas + k);
  k++;
  sort(g.begin(), g.end());
  for (int i = 0; i < n; i++)
    if (g[i].second > mxb) {
      g2.push_back(g[i]);
      mxb = g[i].second;
    }
  l = 0;
  r = g2.size() - 1;
  while (l <= r) {
    m = (l + r) / 2;
    long long time = 0, hg = g2[m].second, lst_x = 0;
    for (int i = 0; i < k; i++) {
      if (hg < gas[i] - lst_x) {
        time = t + 2;
        break;
      }
      hg -= gas[i] - lst_x;
      time += (gas[i] - lst_x) * 2;
      time -= min(hg, gas[i] - lst_x);
      hg = g2[m].second;
      lst_x = gas[i];
    }
    if (time <= t) {
      ans = g2[m].first;
      r = m - 1;
    } else
      l = m + 1;
  }
  printf("%d\n", (int)ans);
  return 0;
}
