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;
const long long MOD = 1e9 + 7;
const long double PI = 4 * atan((long double)1);
const long long INF = 1e18;
const long long NINF = -1e18;
long long get_hash(string s) {
  long long N = 1000001;
  long long base[N], A = 11, MD = 1110111110111;
  base[0] = 1;
  for (long long i = (1); i < (N); ++i) base[i] = (base[i - 1] * A) % MD;
  long long hs = 0;
  for (long long i = (0); i < (s.size()); ++i) {
    hs += (s[i] * base[i]);
    hs %= MD;
  }
  return hs;
}
long long power(long long a, long long n) {
  long long res = 1;
  while (n) {
    if (n % 2) res *= a;
    a *= a;
    n /= 2;
  }
  return res;
}
vector<string> vec_splitter(string s) {
  s += ',';
  vector<string> res;
  while (!s.empty()) {
    res.push_back(s.substr(0, s.find(',')));
    s = s.substr(s.find(',') + 1);
  }
  return res;
}
void debug_out(vector<string> __attribute__((unused)) args,
               __attribute__((unused)) long long idx,
               __attribute__((unused)) long long LINE_NUM) {
  cerr << endl;
}
template <typename Head, typename... Tail>
void debug_out(vector<string> args, long long idx, long long LINE_NUM, Head H,
               Tail... T) {
  if (idx > 0)
    cerr << ", ";
  else
    cerr << "Line(" << LINE_NUM << ") ";
  stringstream ss;
  ss << H;
  cerr << args[idx] << " = " << ss.str();
  debug_out(args, idx + 1, LINE_NUM, T...);
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  long long cst[n], cap[n];
  for (long long i = (0); i < (n); ++i) cin >> cst[i] >> cap[i];
  vector<long long> pp(k + 2);
  pp[0] = 0;
  for (long long i = (0); i < (k); ++i) cin >> pp[i + 1];
  pp[k + 1] = s;
  sort(pp.begin(), pp.end());
  long long lo = 1, hi = 2 * s;
  long long f = 0;
  while (lo < hi) {
    long long mid = lo + (hi - lo) / 2;
    long long time = 0;
    long long e = 0;
    for (long long i = (0); i < (k + 1); ++i) {
      long long dist = pp[i + 1] - pp[i];
      if (dist > mid) {
        e = 1;
        break;
      }
      long long tspd = mid - dist;
      if (tspd > dist) tspd = dist;
      time += tspd + 2 * (dist - tspd);
    }
    if (time > t || e == 1)
      lo = mid + 1;
    else {
      f = 1;
      hi = mid;
    }
  }
  if (f == 0) {
    cout << -1;
    return 0;
  }
  long long min = lo;
  long long mincst = INF;
  for (long long i = (0); i < (n); ++i) {
    if (cap[i] >= min && cst[i] < mincst) mincst = cst[i];
  }
  if (mincst != INF)
    cout << mincst;
  else
    cout << -1;
  return 0;
}
