#include <bits/stdc++.h>
using namespace std;
const long long N = 2 * 1e5 + 100;
long long n, k, s, t, c[N], v[N], g[N], d[N], sum[N];
inline long long read() {
  long long f = 1, x = 0;
  char s = getchar();
  while (s < '0' || s > '9') {
    if (s == '-') f = -1;
    s = getchar();
  }
  while (s >= '0' && s <= '9') {
    x = x * 10 + s - '0';
    s = getchar();
  }
  return x * f;
}
signed main() {
  n = read();
  k = read();
  s = read();
  t = read();
  for (long long i = 1; i <= n; i++) c[i] = read(), v[i] = read();
  for (long long i = 1; i <= k; i++) g[i] = read();
  sort(g + 1, g + 1 + k);
  for (long long i = 1; i <= k; i++) d[i] = g[i] - g[i - 1];
  d[k + 1] = s - g[k];
  k++;
  sort(d + 1, d + 1 + k);
  for (long long i = 1; i <= k; i++) sum[i] = sum[i - 1] + d[i];
  if (t < s) {
    printf("-1\n");
    return 0;
  }
  long long MIN = 0x3f3f3f3f;
  for (long long i = 1; i <= n; i++) {
    if (v[i] < d[k]) continue;
    long long pos = upper_bound(d + 1, d + 1 + k, v[i] / 2) - d - 1;
    long long all = sum[pos] + (sum[k] - sum[pos]) * 3 - (k - pos) * v[i];
    if (all <= t) MIN = min(MIN, c[i]);
  }
  if (MIN == 0x3f3f3f3f)
    printf("-1\n");
  else
    printf("%lld\n", MIN);
}
