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 inf = 987654321;
const long long int INF = 123456789987654321;
int N, K, S, T;
vector<pair<int, int> > car;
vector<int> gas, dist, psum;
void get_psum() {
  psum.resize(dist.size());
  for (int i = 0; i < dist.size(); i++) {
    psum[i] = dist[i];
    if (i != 0) psum[i] += psum[i - 1];
  }
}
int g(int x) {
  int s = 0, e = dist.size() - 1;
  int ret = -1;
  while (s <= e) {
    int m = (s + e) >> 1;
    if (2 * dist[m] <= x) {
      ret = m;
      s = m + 1;
    } else
      e = m - 1;
  }
  return ret;
}
int main() {
  scanf("%d %d %d %d", &N, &K, &S, &T);
  car.resize(N);
  for (int i = 0; i < N; i++) {
    int c, v;
    scanf("%d %d", &c, &v);
    car[i] = pair<int, int>(c, v);
  }
  gas.resize(K);
  for (int i = 0; i < K; i++) {
    scanf("%d", &gas[i]);
  }
  sort(gas.begin(), gas.end());
  dist.push_back(gas[0]);
  for (int i = 1; i < K; i++) {
    dist.push_back(gas[i] - gas[i - 1]);
  }
  dist.push_back(S - gas.back());
  sort(dist.begin(), dist.end());
  get_psum();
  int mini = 2 * inf;
  for (int i = 0; i < N; i++) {
    int f = car[i].second;
    if (dist.back() > f) continue;
    int t = g(f);
    int d = t == -1 ? 0 : psum[t];
    int tm = d;
    tm += 3 * (psum.back() - d) - (dist.size() - 1 - t) * f;
    if (tm <= T) {
      mini = min(mini, car[i].first);
    }
  }
  if (mini != 2 * inf)
    printf("%d", mini);
  else
    printf("-1");
}
