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>
const int inf_int = 2e9;
const long long inf_ll = 2e18;
const int maxn = 5e2 + 10;
using namespace std;
inline int read() {
  int ra, fh;
  char rx;
  rx = getchar(), ra = 0, fh = 1;
  while ((rx < '0' || rx > '9') && rx != '-') rx = getchar();
  if (rx == '-') fh = -1, rx = getchar();
  while (rx >= '0' && rx <= '9') ra *= 10, ra += rx - 48, rx = getchar();
  return ra * fh;
}
long long gcd(long long p, long long q) { return q == 0 ? p : gcd(q, p % q); }
long long qpow(long long p, long long q) {
  long long f = 1;
  while (q) {
    if (q & 1) f = f * p;
    p = p * p;
    q >>= 1;
  }
  return f;
}
bool judge(long long mid);
long long n, k, s, t;
long long c[200005];
long long v[200005];
long long g[200005];
long long re = -1;
long long re1 = inf_ll;
int main(int argc, char** argv) {
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) {
    scanf("%I64d %I64d", &c[i], &v[i]);
  }
  for (int i = 1; i <= k; i++) {
    scanf("%I64d", &g[i]);
  }
  sort(g + 1, g + k + 1);
  g[0] = 0;
  g[k + 1] = s;
  k++;
  long long r = 2 * s;
  long long l = 0;
  while (l < r) {
    long long mid = (l + r) >> 1;
    if (judge(mid)) {
      r = mid;
    } else {
      l = mid + 1;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (v[i] >= re) {
      if (c[i] < re1) {
        re1 = c[i];
      }
    }
  }
  if (re1 == inf_ll) {
    cout << "-1" << endl;
  } else
    cout << re1 << endl;
  return 0;
}
bool judge(long long mid) {
  long long time = 0;
  for (int i = 1; i <= k; i++) {
    long long dis = g[i] - g[i - 1];
    if (dis > mid) return false;
    if (mid >= 2 * dis) {
      time += dis;
    } else {
      time += 3 * dis - mid;
    }
  }
  if (time <= t) {
    re = mid;
    return true;
  } else
    return false;
}
