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 cars, stations, roadlen, timeFilmStarts, cost, fuel, stcord;
vector<pair<int, int>> v;
vector<int> gas;
pair<int, int> res;
bool valid(int x) {
  int tm = 0, dis = 0;
  for (int i = 0; i < gas.size() - 1; i++) {
    dis = gas[i + 1] - gas[i];
    if (x < dis)
      return false;
    else if (x > dis * 2) {
      tm += dis;
    } else {
      tm += x - dis;
      tm += 2 * (dis - (x - dis));
    }
  }
  if (tm > timeFilmStarts)
    return false;
  else
    return true;
}
int bs() {
  int a = 0, b = 1e9 + 1, mid;
  while (a < b) {
    mid = (a + b) / 2;
    if (valid(mid)) {
      b = mid;
    } else {
      a = mid + 1;
    }
  }
  return a;
}
int main() {
  cin >> cars >> stations >> roadlen >> timeFilmStarts;
  for (int i = 0; i < cars; i++) {
    cin >> cost >> fuel;
    v.push_back({fuel, cost});
  }
  gas.push_back(0);
  for (int i = 0; i < stations; i++) {
    cin >> stcord;
    gas.push_back(stcord);
  }
  gas.push_back(roadlen);
  sort(gas.begin(), gas.end());
  sort(v.begin(), v.end());
  res.first = bs();
  res.second = 0;
  auto it = lower_bound(v.begin(), v.end(), res) - v.begin();
  if (it > v.size() - 1)
    puts("-1");
  else
    printf("%d\n", v[it].second);
}
