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 N = 5e5 + 100, M = 2e3 + 9, INF = 1e9 + 7, INF64 = 1e15 + 7;
const long double EPS = 1e-10;
pair<int, int> a[N];
int g[N], k, t;
struct FastIO {
  static const int S = 1310720;
  int wpos;
  char wbuf[S];
  FastIO() : wpos(0) {}
  inline int xchar() {
    static char buf[S];
    static int len = 0, pos = 0;
    if (pos == len) pos = 0, len = fread(buf, 1, S, stdin);
    if (pos == len) return -1;
    return buf[pos++];
  }
  inline int xuint() {
    int c = xchar(), first = 0;
    while (c <= 32) {
      c = xchar();
    }
    for (; '0' <= c && c <= '9'; c = xchar()) first = first * 10 + c - '0';
    return first;
  }
  inline void wchar(int first) {
    if (wpos == S) fwrite(wbuf, 1, S, stdout), wpos = 0;
    wbuf[wpos++] = first;
  }
  inline void wint(int first) {
    if (first < 0) wchar('-'), first = -first;
    char s[24];
    int n = 0;
    while (first || !n) s[n++] = '0' + first % 10, first /= 10;
    while (n--) wchar(s[n]);
  }
  ~FastIO() {
    if (wpos) fwrite(wbuf, 1, wpos, stdout), wpos = 0;
  }
} io;
bool check2(int v, int t, int s) {
  int x1 = 2 * s - t;
  int x2 = v - s;
  int k1 = 2 * s - v;
  int k2 = t - s;
  return x2 >= x1 && k2 >= k1 && x2 >= 0 && k2 >= 0;
}
bool check1(int v) {
  int det, time = 0;
  long long l, r, m;
  for (int i = 0; i < int(k - 1); i++) {
    det = g[i + 1] - g[i];
    l = 0;
    r = t;
    while (r - l > 1) {
      m = (l + r) / 2;
      if (check2(m, v, det))
        r = m;
      else
        l = m;
    }
    time += r;
  }
  return time <= t;
}
int main() {
  int n, s, maxi = -INF, ans = INF, first, second;
  long long l, r, m;
  n = io.xuint();
  k = io.xuint();
  s = io.xuint();
  t = io.xuint();
  for (int i = 0; i < int(n); i++) {
    a[i].first = io.xuint();
    a[i].second = io.xuint();
  }
  g[0] = 0;
  k++;
  for (int i = 1; i < k; i++) {
    g[i] = io.xuint();
  }
  g[k++] = s;
  sort(g, g + k);
  l = 0;
  r = 1e9;
  while (r - l > 1) {
    long long m = (l + r) / 2;
    if (check1(m))
      r = m;
    else
      l = m;
  }
  for (int i = 0; i < int(n); i++)
    if (a[i].second >= r && ans > a[i].first) ans = a[i].first;
  if (ans == INF)
    io.wint(-1);
  else
    io.wint(ans);
  return 0;
}
