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;
}
template <typename T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T chmin(T &x, const T &y) {
  if (y < x) return x = y;
  return x;
}
template <class T>
T chmax(T &x, const T &y) {
  if (x < y) return x = y;
  return x;
}
template <class P, class Q>
ostream &operator<<(ostream &os, const pair<P, Q> &p) {
  return os << '(' << p.first << ", " << p.second << ')';
}
template <class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << '{';
  bool was = false;
  for (const T &x : v) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << '}';
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const set<T> &v) {
  os << '[';
  bool was = false;
  for (const T &x : v) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << ']';
  return os;
}
template <class P, class Q>
ostream &operator<<(ostream &os, const map<P, Q> &m) {
  os << '<';
  bool was = false;
  for (const auto &x : m) {
    if (was) os << ", ";
    was = true;
    os << x;
  }
  os << '>';
  return os;
}
const long long INF = (long long)2e9 + 1;
const long long MAXN = (long long)2e5 + 10;
long long n, k, s, t;
long long cost[MAXN], v[MAXN], pos[MAXN];
long long f(long long V) {
  long long res = 0;
  for (long long i = k + 1; i; i--) {
    if ((pos[i] - pos[i - 1]) > V) {
      return INF;
    }
    if (V >= (pos[i] - pos[i - 1]) * 2)
      res += pos[i] - pos[i - 1];
    else
      res += 3 * (pos[i] - pos[i - 1]) - V;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  for (long long i = 1; i <= n; i++) {
    cin >> cost[i] >> v[i];
  }
  pos[0] = 0, pos[k + 1] = s;
  for (long long i = 1; i <= k; i++) {
    cin >> pos[i];
  }
  sort(pos + 1, pos + k + 1);
  long long l = 1, r = (long long)1e9 + 2;
  while (r - l > 1) {
    long long md = (l + r) >> 1;
    if (f(md) > t)
      l = md;
    else
      r = md;
  }
  long long cc = INF, ans = 0;
  for (int i = 1; i <= n; i++) {
    if (v[i] >= r)
      if (cc > cost[i]) cc = cost[i], ans = i;
  }
  if (cc == INF)
    cout << -1;
  else
    cout << cc;
}
