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;
int n, k;
long long s, t;
vector<long long> price;
vector<long long> tank;
vector<long long> gas;
int compute(int car) {
  int time = 0;
  for (int i = (0); i < ((int)(gas.size()) - 1); ++i) {
    long long dist = gas[i + 1] - gas[i];
    if (dist >= tank[car]) return 0;
    time += dist + max(0LL, dist - (tank[car] - dist));
  }
  if (time <= t) return 1;
  return 0;
}
int main() {
  cin >> n >> k >> s >> t;
  tank.resize(n);
  price.resize(n);
  gas.resize(n);
  for (int i = (0); i < (n); ++i) cin >> price[i] >> tank[i];
  for (int i = (0); i < (k); ++i) cin >> gas[i];
  gas.push_back(s);
  gas.push_back(0);
  sort(gas.begin(), gas.end());
  long long minprice = 1.5e9;
  for (int i = (0); i < (n); ++i)
    if (compute(i)) minprice = min(minprice, price[i]);
  cout << minprice << endl;
  return 0;
}
