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>
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops", \
                     "omit-frame-pointer", "inline")
#pragma GCC target( \
    "sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx,avx2,fma,tune=native")
#pragma GCC option("arch=native", "no-zero-upper")
using namespace std;
const long long oo = (long long)(1e18);
vector<long long> dis;
long long solve(long long x) {
  long long res = 0;
  for (auto y : dis) {
    if (y > x) return 1e18;
    long long best = min(x - y, y);
    res += 2 * y - best;
  }
  return res;
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long n, k, second, t;
  cin >> n >> k >> second >> t;
  vector<pair<long long, long long> > cars;
  for (int i = 0; i < n; i++) {
    int c, v;
    cin >> c >> v;
    cars.push_back(pair<long long, long long>(c, v));
  }
  sort((cars).begin(), (cars).end());
  vector<pair<long long, long long> > nc;
  nc.push_back(cars[0]);
  for (int i = 1; i < n; i++)
    if (cars[i].second > nc.back().second) nc.push_back(cars[i]);
  cars = nc;
  n = cars.size();
  vector<int> ps;
  ps.push_back(0);
  for (int i = 0; i < k; i++) {
    int x;
    cin >> x;
    ps.push_back(x);
  }
  ps.push_back(second);
  sort((ps).begin(), (ps).end());
  for (int i = 1; i < ps.size(); i++) dis.push_back(ps[i] - ps[i - 1]);
  int pos = -1;
  for (int po = (1 << 17); po; po >>= 1)
    if (pos + po < n && solve(cars[pos + po].second) > t) pos += po;
  pos++;
  if (pos == n)
    cout << (-1) << '\n';
  else
    cout << (cars[pos].first) << '\n';
  return 0;
}
