1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
pair<int, int> car[MAXN];
int g[MAXN], pref[MAXN];
int n, k, s, t;
bool check(int v) {
  int needTime = 0;
  int dist;
  for (int i = 1; i <= k + 1; i++) {
    dist = g[i] - g[i - 1];
    if (v >= 2 * dist) {
      needTime += dist;
    } else {
      needTime += (2 * dist - v % dist);
    }
  }
  return (needTime <= t) ? true : false;
}
int main() {
  ios_base::sync_with_stdio(false);
  int ans, mx, lg, rg, mid;
  bool flag;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    cin >> car[i].first >> car[i].second;
  }
  sort(car, car + n);
  memset(pref, 0, sizeof(pref));
  pref[0] = car[0].second;
  for (int i = 1; i < n; i++) {
    pref[i] = max(pref[i - 1], car[i].second);
  }
  g[0] = 0;
  for (int i = 1; i <= k; i++) cin >> g[i];
  g[k + 1] = s;
  sort(g, g + k + 1);
  mx = 0;
  for (int i = 1; i <= k + 1; i++) mx = max(mx, g[i] - g[i - 1]);
  lg = 0;
  rg = n;
  while (rg - lg > 1) {
    mid = (lg + rg) / 2;
    if (pref[mid] < mx) {
      lg = mid;
      continue;
    }
    if (check(pref[mid]))
      rg = mid;
    else
      lg = mid;
  }
  if (rg == n) {
    if ((mx <= pref[lg]) && (check(pref[lg]))) {
      cout << car[lg].first << endl;
    } else {
      cout << -1 << endl;
    }
  } else {
    if ((mx <= pref[lg]) && (check(pref[lg]))) {
      cout << car[lg].first << endl;
    } else {
      cout << car[rg].first << endl;
    }
  }
  return 0;
}
