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;
long long bs1(long long s, long long mid1) {
  long long l = -1, r = s + 1;
  while (l + 1 < r) {
    long long mid = l + (r - l) / 2;
    if (mid * 2 + s - mid <= mid1) {
      l = mid;
    } else {
      r = mid;
    }
  }
  return l;
}
long long check(long long t, long long mid, long long k,
                vector<long long> &gas) {
  long long ct = 0, s2, s;
  for (int i = 0; i <= k; ++i) {
    s = gas[i + 1] - gas[i];
    s2 = bs1(s, mid);
    if (s2 < 0) {
      return 0;
    }
    ct += (s - s2) * 2 + s2;
  }
  return ct <= t;
}
long long bs(long long t, long long k, vector<long long> &gas) {
  long long l = 0, r = t;
  while (l + 1 < r) {
    int mid = l + (r - l) / 2;
    if (check(t, mid, k, gas)) {
      r = mid;
    } else {
      l = mid;
    }
  }
  return r;
}
int main() {
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  if (s > t) {
    cout << -1 << endl;
    return 0;
  }
  vector<pair<long, long>> cars(n);
  vector<long long> gas(k + 2);
  for (int i = 0; i < n; ++i) {
    cin >> cars[i].first >> cars[i].second;
  }
  for (int i = 1; i <= k; ++i) {
    cin >> gas[i];
  }
  gas[0] = 0;
  gas[k + 1] = s;
  sort(gas.begin(), gas.end());
  long long ans = 1000000001;
  long long minv = bs(t, k, gas);
  for (int i = 0; i < n; ++i) {
    if (cars[i].second >= minv) {
      if (ans > cars[i].first) {
        ans = cars[i].first;
      }
    }
  }
  cout << ans << endl;
}
