#include <bits/stdc++.h>
template <typename T>
inline T max(T a, T b) {
  return a > b ? a : b;
}
template <typename T>
inline T min(T a, T b) {
  return a < b ? a : b;
}
template <typename T>
inline T abs(T a) {
  return a > 0 ? a : -a;
}
template <typename T>
inline void repr(T &a, T b) {
  if (a < b) a = b;
}
template <typename T>
inline void repl(T &a, T b) {
  if (a > b) a = b;
}
template <typename T>
T gcd(T a, T b) {
  if (b) return gcd(b, a % b);
  return a;
}
int n, k, s, t, g[200002];
struct hh {
  int c, v;
  bool operator<(hh x) const { return c < x.c; }
} u[200000];
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) scanf("%d%d", &u[i].c, &u[i].v);
  std::sort(u, u + n);
  for (int i = 0; i < k; i++) scanf("%d", g + i);
  g[k] = 0, g[k + 1] = s;
  std::sort(g, g + k + 2);
  int l = 0, r = 2000000000;
  while (r - l > 1) {
    int p = (l + r) / 2;
    long long tm = 0;
    for (int i = 0; i <= k; i++) {
      if (p < g[i + 1] - g[i]) {
        tm = 0x7fffffffffffffff;
        break;
      }
      tm += max((long long)(g[i + 1] - g[i]) * 3 - p,
                (long long)(g[i + 1] - g[i]));
    }
    if (tm > t)
      l = p;
    else
      r = p;
  }
  for (int i = 0; i < n; i++)
    if (u[i].v >= r) {
      printf("%d", u[i].c);
      return 0;
    }
  puts("-1");
}
