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 INF = 1 << 28;
const long long LINF = 1ll << 61;
inline long long getnum() {
  register long long r = 0;
  register bool ng = 0;
  register char c;
  c = getchar();
  while (c != '-' && (c < '0' || c > '9')) c = getchar();
  if (c == '-') ng = 1, c = getchar();
  while (c >= '0' && c <= '9') r = r * 10 + c - '0', c = getchar();
  if (ng) r = -r;
  return r;
}
template <class T>
inline void putnum(T x) {
  if (x < 0) putchar('-'), x = -x;
  register short a[20] = {}, sz = 0;
  while (x > 0) a[sz++] = x % 10, x /= 10;
  if (sz == 0) putchar('0');
  for (int i = sz - 1; i >= 0; i--) putchar('0' + a[i]);
}
inline void putsp() { putchar(' '); }
inline void putendl() { putchar('\n'); }
inline char mygetchar() {
  register char c = getchar();
  while (c == ' ' || c == '\n') c = getchar();
  return c;
}
int n, m;
long long s, t, pos[200111];
long long tc[200111], tv[200111];
bool check(long long x) {
  long long ti = 0;
  for (int i = 0; i <= m; i++) {
    long long len = pos[i + 1] - pos[i];
    if (len > x) return false;
    if (len <= x / 2) {
      ti += len;
    } else {
      ti += (x - len) + 2 * (len - (x - len));
    }
  }
  return ti <= t;
}
int main() {
  n = getnum(), m = getnum();
  s = getnum(), t = getnum();
  for (int i = 1; i <= n; i++) tc[i] = getnum(), tv[i] = getnum();
  for (int i = 1; i <= m; i++) {
    pos[i] = getnum();
  }
  sort(pos + 1, pos + m + 1);
  pos[0] = 0;
  pos[m + 1] = s;
  long long l = 1, r = 1ll << 50;
  while (l <= r) {
    long long mid = l + r >> 1;
    if (check(mid))
      r = mid - 1;
    else
      l = mid + 1;
  }
  long long ans = 1ll << 50;
  for (int i = 1; i <= n; i++) {
    if (tv[i] < l) continue;
    ans = min(ans, tc[i]);
  }
  if (ans == (1ll << 50))
    puts("-1");
  else
    cout << ans << endl;
  return 0;
}
