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 max_n = 1e6 + 5;
long long int wynik[max_n];
int main() {
  int(n), (k);
  scanf("%d%d", &(n), &(k));
  ;
  int(s), (t);
  scanf("%d%d", &(s), &(t));
  ;
  vector<pair<int, int> > cars;
  for (int i = (0); i < (n); ++i) {
    int(a), (b);
    scanf("%d%d", &(a), &(b));
    ;
    cars.push_back(make_pair(b, a));
  }
  vector<int>(v);
  for (int i = (0); i < ((k)); ++i) {
    int(a);
    scanf("%d", &(a));
    ;
    (v).push_back(a);
  };
  sort((v).begin(), (v).end());
  int start = 0, meta = s;
  vector<int> x;
  for (int i = (0); i < (k); ++i) {
    if (i == 0)
      x.push_back(v[i]);
    else
      x.push_back(v[i] - v[i - 1]);
  }
  x.push_back(meta - v[k - 1]);
  sort((x).begin(), (x).end());
  sort((cars).begin(), (cars).end());
  int best = 1e9 + 5;
  for (int i = (0); i < (cars.size()); ++i) {
    if (cars[i].first < x.back()) continue;
    wynik[i] = 3LL * s - cars[i].first * 1LL * x.size();
  }
  long long int minus = 0;
  int ile = 0;
  int xpos = 0;
  for (int i = (0); i < (cars.size()); ++i) {
    if (cars[i].first < x.back()) continue;
    while (xpos < x.size() && cars[i].first >= 2 * x[xpos]) {
      ile++;
      minus += 2 * x[xpos];
      xpos++;
    }
    wynik[i] += cars[i].first * 1LL * ile - minus;
    if (wynik[i] <= t) {
      best = min(best, cars[i].second);
    }
  }
  if (best == 1e9 + 5)
    printf("-1\n");
  else
    printf("%d\n", best);
}
