#include <bits/stdc++.h>
int cmp(const void *a, const void *b) { return *(int *)a - *(int *)b; }
long long n, k, s, t;
struct data {
  long long price;
  long long fuel;
} x[200005];
long long g[200005];
int judge(int f) {
  int i;
  long long time = 0, len = 0;
  for (i = 1; i <= k + 1; i++) {
    long long d = g[i] - g[i - 1];
    if (f < d) return 0;
    if (len + d < s) {
      len += d;
      long long a1 = f - d > d ? d : f - d;
      long long a2 = d - a1;
      time += (a1 + 2 * a2);
    } else {
      d = s - len;
      long long a1 = f - d > d ? d : f - d;
      long long a2 = d - a1;
      time += (a1 + 2 * a2);
      break;
    }
  }
  return time <= t ? 1 : 0;
}
int bs(int left, int right) {
  int mid = (left + right) / 2;
  while (left <= right) {
    if (judge(mid) == 0)
      left = mid + 1;
    else
      right = mid - 1;
    mid = (left + right) / 2;
  }
  return left;
}
int main() {
  scanf("%I64d %I64d %I64d %I64d", &n, &k, &s, &t);
  int i;
  long long min = INT_MAX;
  for (i = 0; i < n; i++) scanf("%I64d %I64d", &x[i].price, &x[i].fuel);
  for (i = 1; i <= k; i++) scanf("%I64d", &g[i]);
  g[k + 1] = s;
  qsort(g, k + 1, sizeof(long long), cmp);
  int line = bs(1, 1000000000);
  for (i = 0; i < n; i++) {
    if (x[i].fuel >= line)
      if (x[i].price < min) min = x[i].price;
  }
  if (min != INT_MAX)
    printf("%d", min);
  else
    puts("-1");
}
