#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e18;
int main() {
  std::ios::sync_with_stdio(false);
  long long n, k, s, t;
  scanf("%lld %lld %lld %lld", &n, &k, &s, &t);
  std::vector<long long> shit(n), shit2(n);
  for (int i = 0; i < n; ++i) {
    scanf("%lld", &shit[i]);
    scanf("%lld", &shit2[i]);
  }
  std::vector<long long> g(k);
  for (int i = 0; i < k; ++i) scanf("%lld", &g[i]);
  g.push_back(0);
  sort(g.begin(), g.end());
  g.push_back(s);
  long long answ = inf;
  long long l = 0, r = inf;
  while (r - l > 1) {
    long long v = (l + r) / 2;
    long long curVR = 0;
    for (int j = 0; j < k + 1; ++j) {
      long long dist = abs(g[j] - g[j + 1]);
      if (dist > v) {
        curVR = inf;
        break;
      }
      if (dist > v / 2) {
        curVR += 3 * dist - v;
      } else {
        curVR += dist;
      }
    }
    if (curVR > t) {
      l = v;
    }
    if (curVR <= t) {
      r = v;
    }
  }
  for (int i = 0; i < n; ++i) {
    if (shit2[i] >= r) {
      answ = std::min(answ, shit[i]);
    }
  }
  if (answ == inf)
    std::cout << -1;
  else
    std::cout << answ;
}
