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 long long MAXN = 200000;
const long long INF = 2e9 + 1;
long long n, m, s, t, c[MAXN + 5], v[MAXN + 5], x[MAXN + 5];
long long calc(long long v) {
  long long res = 0, last = 0;
  for (int i = 0; i < m; ++i) {
    long long dist = x[i] - last;
    if (dist > v) return INF;
    if (dist * 2 <= v) {
      res += x[i] - last;
    } else {
      long long tmp = v - dist;
      res += tmp + (dist - tmp) * 2;
    }
    last = x[i];
  }
  return res;
}
long long search() {
  long long lef = 0, rig = INF;
  while (lef < rig) {
    long long mid = (lef + rig) / 2;
    if (calc(mid) <= t) {
      rig = mid;
    } else {
      lef = mid + 1;
    }
  }
  return lef;
}
int main() {
  scanf("%lld %lld %lld %lld", &n, &m, &s, &t);
  for (int i = 0; i < n; ++i) scanf("%lld %lld", c + i, v + i);
  for (int i = 0; i < m; ++i) scanf("%lld", x + i);
  x[m++] = s;
  sort(x, x + m);
  long long mn = search();
  long long res = -1;
  for (int i = 0; i < n; ++i)
    if (v[i] >= mn) {
      if (res == -1 || c[i] < res) res = c[i];
    }
  printf("%lld\n", res);
  return 0;
}
