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 Max = 1e6 + 7;
long long w[Max], v[Max];
long long p[Max];
long long a[Max];
int main() {
  long long n, m, s, t;
  scanf("%lld%lld%lld%lld", &n, &m, &s, &t);
  for (int i = 1; i <= n; i++) {
    scanf("%lld%lld", &w[i], &v[i]);
  }
  for (int i = 1; i <= m; i++) scanf("%lld", &p[i]);
  sort(p + 1, p + 1 + m);
  p[0] = 0, p[m + 1] = s;
  long long mmax = 0;
  if (s > t) {
    cout << -1 << endl;
  } else {
    long long x = (t - s) * 2;
    x = min(t, x);
    long long y = t - x;
    long long mmax = 0;
    for (int i = 1; i <= m + 1; i++) {
      a[i] = p[i] - p[i - 1];
    }
    sort(a + 1, a + 1 + m + 1);
    int flag = 1;
    for (int i = 1; i <= m + 1; i++) {
      if (y != 0) {
        if (y >= a[i]) {
          mmax = max(mmax, 2 * a[i]);
          y -= a[i];
        } else {
          mmax = max(mmax, y * 2 + a[i] - y);
          y == 0;
        }
      } else {
        mmax = max(mmax, a[i]);
      }
    }
    long long c = 0x3f3f3f3f;
    for (int i = 1; i <= n; i++) {
      if (v[i] >= mmax) {
        flag = 0;
        c = min(c, w[i]);
      }
    }
    if (flag == 1)
      cout << -1 << endl;
    else
      cout << c << endl;
  }
  return 0;
}
