#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const int SIZE = 1e6 + 5;
const long long INF = 1LL << 60;
const double eps = 1e-4;
const double PI = 3.1415926535897932;
int x[200009];
pair<int, int> vv[200009];
vector<pair<int, int> > v;
int main() {
  int n, k;
  scanf("%d%d", &n, &k);
  int s, t;
  scanf("%d%d", &s, &t);
  for (int i = 0; i < (n); ++i) {
    scanf("%d%d", &(vv[i].first), &(vv[i].second));
  }
  sort(vv, vv + n);
  for (int i = 0; i < (n); ++i) {
    if (i == 0 || vv[i].second > v.back().second) {
      v.push_back(vv[i]);
    }
  }
  n = ((int)(v).size());
  for (int i = 0; i < (k); ++i) {
    scanf("%d", &(x[i]));
  }
  sort(x, x + k);
  x[k] = s;
  int st = 0, en = n;
  while (st < en) {
    int mi = (st + en) / 2;
    int ts = v[mi].second;
    long long mint = 0;
    for (int i = 0; i < (k + 1); ++i) {
      int rl = i ? x[i] - x[i - 1] : x[i];
      if (rl > ts) {
        mint = INF;
        break;
      }
      mint += max(2LL * (long long)rl - (long long)(ts - rl), (long long)rl);
    }
    if (mint <= t) {
      en = mi;
    } else {
      st = mi + 1;
    }
  }
  if (en == n)
    printf("-1");
  else
    printf("%d", v[st].first);
}
