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;
int n, k, s, t;
vector<pair<int, int> > cars;
int gas[1000000];
int accdist, normdist;
int computeBestAcceleratedDist(int totaldist, int carCapacity) {
  int l = 0, r = totaldist + 1, mid, maxacc = 0;
  while (l < r) {
    mid = (l + r) / 2;
    if (mid * 2 + (totaldist - mid) <= carCapacity) {
      maxacc = max(maxacc, mid);
      l = mid + 1;
    } else
      r = mid;
  }
  return maxacc;
}
bool ok(int carIdx) {
  int v = cars[carIdx].first;
  int c = cars[carIdx].second;
  int dist, time = 0;
  for (int i = 1; i < k; i++) {
    dist = gas[i] - gas[i - 1];
    accdist = computeBestAcceleratedDist(dist, c);
    normdist = dist - accdist;
    if (accdist * 2 + normdist > c) return false;
    time += accdist + 2 * normdist;
    if (time < 0 || time > t) return false;
  }
  return true;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  map<int, int> mp;
  int v, c;
  for (int i = 0; i < n; i++) {
    scanf("%d %d", &v, &c);
    if (mp.find(v) != mp.end())
      mp[v] = min(mp[v], c);
    else
      mp[v] = c;
  }
  for (map<int, int>::iterator it = mp.begin(); it != mp.end(); it++) {
    cars.push_back(make_pair(it->first, it->second));
  }
  gas[0] = 0;
  for (int i = 1; i <= k; i++) scanf("%d", &gas[i]);
  k++;
  sort(gas, gas + k);
  gas[k] = s;
  k++;
  int l = 0, r = n, mid, minn = INT_MAX;
  while (l < r) {
    mid = (l + r) / 2;
    if (ok(mid)) {
      minn = min(minn, mid);
      r = mid;
    } else
      l = mid + 1;
  }
  printf("%d\n", cars[minn].first);
  return 0;
}
