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 = 1e9 + 100;
struct car {
  int c, v;
  bool operator<(const car& other) const {
    if (v != other.v) {
      return v < other.v;
    }
    return c < other.c;
  }
};
int main() {
  int n, k, s, t;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  vector<car> cars(n);
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &cars[i].c, &cars[i].v);
  }
  sort((cars).begin(), (cars).end());
  vector<int> a(k);
  a.push_back(0);
  for (int i = 0; i < k; ++i) {
    scanf("%d", &a[i]);
  }
  sort((a).begin(), (a).end());
  vector<int> dist;
  a.push_back(s);
  for (int i = 1; i < (int)(a).size(); ++i) {
    dist.push_back(a[i] - a[i - 1]);
  }
  sort((dist).begin(), (dist).end());
  int ans = inf;
  int ptr = 0;
  int sum = 0;
  for (int i = 0; i < n; ++i) {
    if (cars[i].v < dist.back()) {
      continue;
    }
    while (ptr < (int)(dist).size() && 2 * dist[ptr] <= cars[i].v) {
      sum += dist[ptr];
      ++ptr;
    }
    long long val = long long(sum) + long long(3) * long long(s - sum) -
                    long long(cars[i].v) * long long(ptr);
    if (val <= t) {
      ans = min(ans, cars[i].c);
    }
  }
  cout << (ans == inf ? -1 : ans) << "\n";
}
