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;
bool less_vectors(const vector<int>& a, const vector<int>& b) {
  return a.size() > b.size();
}
long long gcd(long long a, long long b) {
  if (a % b == 0)
    return b;
  else
    return gcd(b, a % b);
}
class compr {
 public:
  bool operator()(pair<pair<int, long long>, int> p1,
                  pair<pair<int, long long>, int> p2) {
    if (p1.first.second != p2.first.second)
      return p1.first.second > p2.first.second;
    else if (p1.second != p2.second)
      return p1.second > p2.second;
    else
      return p1.first < p2.first;
  }
};
long long fastexpo(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b % 2 == 1)
      res = (((res) % 1000000007) * ((a) % 1000000007)) % 1000000007;
    a = (((a) % 1000000007) * ((a) % 1000000007)) % 1000000007;
    b /= 2;
  }
  return res;
}
long long fastexpom(long long a, long long b, long long m) {
  long long res = 1;
  while (b > 0) {
    if (b % 2 == 1) res = (((res) % m) * ((a) % m)) % m;
    a = (((a) % m) * ((a) % m)) % m;
    b /= 2;
  }
  return res;
}
long long modinv(long long a, long long m = 1000000007) {
  return fastexpom(a, m - 2, m);
}
vector<long long> pos;
int k;
bool check(long long m, int time) {
  int t = 0;
  bool ch = 1;
  int fuel = m;
  for (int i = 0; i <= k; i++) {
    long long t1 = 0;
    long long d = pos[i + 1] - pos[i];
    t1 = 2 * d;
    m = fuel;
    m -= d;
    if (m < 0) {
      ch = 0;
      break;
    }
    t1 -= min(d, m);
    t += t1;
  }
  if (t <= time)
    ;
  else
    ch = 0;
  return ch;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n, s, t;
  cin >> n >> k >> s >> t;
  long long hi = 0;
  vector<pair<long long, long long> > v(n);
  pos.resize(k + 2);
  for (int i = 0; i < n; i++) {
    cin >> v[i].first >> v[i].second;
    hi = max(hi, v[i].second);
  }
  for (int i = 1; i <= k; i++) cin >> pos[i];
  pos[0] = 0;
  pos[k + 1] = s;
  ;
  sort(pos.begin(), pos.end());
  hi = hi + 1;
  long long lo = 0;
  while (lo < hi) {
    int mid = (lo + hi) >> 1;
    if (check(mid, t)) {
      hi = mid;
    } else
      lo = mid + 1;
  }
  sort(v.begin(), v.end());
  long long ans = INT_MAX;
  for (int i = 0; i < n; i++) {
    if (v[i].second >= lo) ans = min(ans, v[i].first);
  }
  if (ans != INT_MAX)
    cout << ans;
  else
    cout << -1;
  return 0;
}
