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>
#pragma comment(linker, "/stack:16777216")
using namespace std;
const int INF = 1000000000;
const int MAX = 100007;
const int MAX2 = 1000000;
const int MAXD = 20;
const int BASE = 1000000007;
const int MOD = 1000000007;
int n, k, s, t;
vector<int> A, B;
vector<pair<int, int> > C;
bool F(int x) {
  int sum = 0;
  for (int i = 0; i < (int)B.size(); ++i) {
    if (x < B[i]) return 0;
    sum += 2 * B[i] - min(x - B[i], B[i]);
  }
  return sum <= t;
}
int main() {
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > CC;
  for (int i = (0); i < (n); i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    CC.push_back(make_pair(y, x));
  }
  sort(CC.begin(), CC.end());
  for (int i = (0); i < ((int)CC.size()); i++) {
    while ((int)C.size() && C.back().second >= CC[i].second) C.pop_back();
    if (C.empty() || CC[i].first > C.back().first) C.push_back(CC[i]);
  }
  for (int i = (0); i < (k); i++) {
    int x;
    cin >> x;
    A.push_back(x);
  }
  A.push_back(0);
  A.push_back(s);
  sort(A.begin(), A.end());
  A.resize(unique(A.begin(), A.end()) - A.begin());
  for (int i = (0); i < ((int)A.size() - 1); i++) {
    B.push_back(A[i + 1] - A[i]);
  }
  int L = 0;
  int R = (int)C.size() - 1;
  if (!F(C[R].first)) {
    cout << -1 << endl;
    return 0;
  }
  while (R - L > 1) {
    int X = (L + R) / 2;
    if (F(C[X].first))
      R = X;
    else
      L = X;
  }
  if (F(C[L].first)) R = L;
  cout << C[R].second;
  return 0;
}
