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>
ostream& operator<<(ostream& cout, const vector<T>& a) {
  if ((int)a.size() == 0) {
    return (cout << "()");
  }
  cout << "(" << a[0];
  for (int i = 1; i < (int)a.size(); i++) {
    cout << "; " << a[i];
  }
  return (cout << ")");
}
template <typename T>
ostream& operator<<(ostream& cout, const set<T>& a) {
  if ((int)a.size() == 0) {
    return (cout << "{}");
  }
  auto it = a.begin();
  cout << "{" << *it;
  ++it;
  for (; it != a.end(); ++it) {
    cout << "; " << *it;
  }
  return (cout << "}");
}
template <typename T>
ostream& operator<<(ostream& cout, const multiset<T>& a) {
  if ((int)a.size() == 0) {
    return (cout << "{}");
  }
  auto it = a.begin();
  cout << "{" << *it;
  ++it;
  for (; it != a.end(); ++it) {
    cout << "; " << *it;
  }
  return (cout << "}");
}
template <typename T1, typename T2>
ostream& operator<<(ostream& cout, const pair<T1, T2>& a) {
  return cout << "(" << a.first << "; " << a.second << ")";
}
const int nmax = 2000 * 1000;
const int inf = 1000 * 1000 * 1000;
const long long infl = 1000ll * 1000ll * 1000ll * 1000ll * 1000ll * 1000ll;
const int mod = 1000 * 1000 * 1000 + 7;
const long double pi = acos(-1.0);
long long n, k, s, t;
long long g[nmax], c[nmax], v[nmax];
bool check(int m) {
  long long tim = 0;
  for (int i = 0; i < k; i++) {
    long long len = (i == 0 ? g[i] : g[i] - g[i - 1]);
    if (len * 2 <= m) {
      tim += len;
    } else if (len * 2 > m) {
      tim += (long long)(2 * len - m) * 2 + (m - len);
    } else if (len > m) {
      return false;
    }
  }
  return tim <= t;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    scanf("%lld %lld", &c[i], &v[i]);
  }
  for (int i = 0; i < k; i++) {
    scanf("%lld", &g[i]);
  }
  g[k++] = s;
  sort(g, g + k);
  long long l = -1, r = inf + 10;
  while (r - l > 1) {
    int m = (l + r) / 2;
    if (check(m)) {
      r = m;
    } else {
      l = m;
    }
  }
  long long answer = infl;
  for (int i = 0; i < k; i++) {
    if (v[i] >= r) {
      answer = min(answer, c[i]);
    }
  }
  if (answer == infl) {
    cout << -1 << endl;
  } else {
    cout << answer << endl;
  }
  return 0;
}
