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;
template <typename T>
T sqr(T x) {
  return x * x;
}
inline unsigned long long bit(int num) { return 1ull << num; }
long long T;
vector<int> ds;
bool Can(long long v) {
  if (ds.back() > v) return false;
  long long t = 0;
  for (int i = 0; i < int(ds.size()); ++i) {
    long long d = ds[i];
    long long t1 = 4 * d - 2 * v;
    long long t2 = v - d;
    if (t1 < 0) {
      t += d;
    } else {
      t += t1 + t2;
    }
  }
  return t <= T;
}
long long Bins(long long l, long long r) {
  while (l < r) {
    long long m = (l + r) / 2;
    if (!Can(m)) {
      l = m + 1;
    } else {
      r = m;
    }
  }
  return l;
}
int main() {
  long long n, k, s;
  cin >> n >> k >> s >> T;
  vector<pair<long long, long long> > cars(n);
  vector<long long> pts(k);
  ds.resize(k + 1);
  for (int i = 0; i < int(n); ++i) {
    cin >> cars[i].first >> cars[i].second;
  }
  for (int i = 0; i < int(k); ++i) {
    cin >> pts[i];
  }
  sort((pts).begin(), (pts).end());
  pts.push_back(s);
  ds[0] = pts[0];
  for (int i = 0; i < int(k); ++i) {
    ds[i + 1] = pts[i + 1] - pts[i];
  }
  sort((ds).begin(), (ds).end());
  long long l = 0;
  long long r = 1e14;
  long long minV = Bins(l, r);
  long long res = LLONG_MAX;
  for (int i = 0; i < int(n); ++i) {
    long long cost = cars[i].first;
    long long v = cars[i].second;
    if (v >= minV) {
      res = min(res, cost);
    }
  }
  if (res == LLONG_MAX) res = -1;
  cout << res << endl;
  return 0;
}
