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 int N = 2e5 + 10;
int n, k, s, t;
struct Node {
  int c, v;
} car[N];
int gas[N];
bool comp(const Node& a, const Node& b) {
  if (a.c == b.c) return a.v < b.v;
  return a.c < b.c;
}
bool solve(int num) {
  int ti = 0;
  for (int i = 1; i <= k + 1; i++) {
    if (gas[i] - gas[i - 1] > car[num].v) return false;
    if ((gas[i] - gas[i - 1]) * 2 <= car[num].v)
      ti += gas[i] - gas[i - 1];
    else
      ti += 3 * (gas[i] - gas[i - 1]) - car[num].v;
    if (ti > t) return false;
  }
  return true;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) scanf("%d %d", &car[i].c, &car[i].v);
  sort(car, car + n, comp);
  for (int i = 1; i <= k; i++) scanf("%d", &gas[i]);
  gas[k + 1] = s;
  sort(gas, gas + k + 2);
  int l = 0, r = n - 1, mid;
  while (l < r) {
    mid = (l + r) >> 1;
    if (solve(mid))
      r = mid;
    else
      l = mid + 1;
  }
  if (solve(r))
    printf("%d", car[r].c);
  else
    printf("-1");
  return 0;
}
