#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline T SQR(T x) {
  return x * x;
}
template <typename T>
inline void UPDATE_MIN(T &x, T y) {
  if (y < x) {
    x = y;
  }
}
template <typename T>
inline void UPDATE_MAX(T &x, T y) {
  if (x < y) {
    x = y;
  }
}
template <typename T>
inline int ARGMAX(T cont) {
  return max_element(cont.begin(), cont.end()) - cont.begin();
}
template <typename T>
inline int ARGMIN(T cont) {
  return min_element(cont.begin(), cont.end()) - cont.begin();
}
template <typename T>
inline int hamming(T x) {
  return __builtin_popcountll((long long)x);
}
int hamming(int x) { return __builtin_popcount(x); }
int hamming(long x) { return __builtin_popcountl(x); }
int hamming(long long x) { return __builtin_popcountll(x); }
vector<string> split(const string &s, char c) {
  vector<string> v;
  stringstream ss(s);
  string x;
  while (getline(ss, x, c)) v.emplace_back(x);
  return move(v);
}
template <typename T, typename... Args>
inline string arrStr(T arr, int n) {
  stringstream s;
  s << "[";
  for (__typeof(n - 1) i = (0), __tmpvar__end89 = (n - 1); i < __tmpvar__end89;
       i++)
    s << arr[i] << ",";
  s << arr[n - 1] << "]";
  return s.str();
}
template <class T>
inline string TOSTR(const T &x) {
  stringstream ss;
  ss << x;
  return ss.str();
}
inline void DIER(char *res, char *dbg = NULL) {
  fprintf(stderr, "[!] die reason %s\n", dbg);
  puts(res);
  exit(0);
}
inline void PR(void) {}
inline void PR(int x) { printf("%d", x); }
inline void PR(long long x) { printf("%lld", x); }
inline void PR(size_t x) { printf("%llu", (unsigned long long)x); }
inline void PR(const char *s) { printf("%s", s); }
inline void PR(double f) { printf("%.10f", f); }
inline void PR(long double f) { printf("%.10f", (double)f); }
template <typename T>
inline void PR(vector<T> &vec) {
  auto sz = vec.size();
  for (auto x : vec) {
    PR(x);
    (--sz) ? putc(0x20, stdout) : 0;
  }
}
template <typename T>
inline void PRS(T x) {
  PR(x);
  putc(0x20, stdout);
}
template <typename T>
inline void PRN(T x) {
  PR(x);
  putc(0x0a, stdout);
}
void PRN(void) { putc(0x0a, stdout); }
struct pairhash {
  template <typename T, typename U>
  std::size_t operator()(const std::pair<T, U> &x) const {
    return std::hash<T>()(x.first) ^ std::hash<U>()(x.second);
  }
};
const int MOD = 1000 * 1000 * 1000 + 7;
const double PI = 3.1415926535897932384626433832795l;
template <typename T>
inline T gcd(T a, T b) {
  return a ? gcd(b % a, a) : b;
}
inline void addto(int &a, int b) {
  a += b;
  if (a >= MOD) a -= MOD;
}
inline int add(int a, int b) {
  a += b;
  if (a >= MOD) a -= MOD;
  return a;
}
inline void subto(int &a, int b) {
  a -= b;
  if (a < 0) a += MOD;
  if (a >= MOD) a -= MOD;
}
inline int sub(int a, int b) {
  a -= b;
  if (a < 0) a += MOD;
  if (a >= MOD) a -= MOD;
  return a;
}
inline void multo(int &a, int b) { a = (long long)a * b % MOD; }
inline int mul(int a, int b) { return (long long)a * b % MOD; }
inline int mulmod(int a, int b, int mod) { return (long long)a * b % mod; }
inline int powmod(int a, int e, int mod) {
  int x;
  for (x = 1; e > 0; e >>= 1) {
    if (e & 1) x = mulmod(x, a, mod);
    a = mulmod(a, a, mod);
  }
  return x;
}
inline int invmod_prime(int a, int mod) { return powmod(a, mod - 2, mod); }
inline long long invmod_LL(long long p) {
  long long q = p;
  for (long long a = p * p; a != 1; a *= a) q *= a;
  return q;
}
template <typename F, typename T>
T binary_search_first_good(T l, T r, F good) {
  T res = -1;
  while (r >= l) {
    T mid = (l + r) >> 1;
    if (good(mid)) {
      res = mid;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }
  return res;
}
int N, M, K, L, E, Q, S, T;
pair<int, int> cars[200123];
vector<int> dists;
bool isgood(long long vol) {
  long long tot = 0;
  for (auto &d : dists) {
    if (d > vol) return false;
    long long num1 = max(0ll, 2 * d - vol);
    num1 = min(num1, (long long)d);
    long long num2 = d - num1;
    tot += 2 * num1 + num2;
  }
  1;
  return (tot <= T);
}
int main() {
  ios_base::sync_with_stdio(0);
  scanf("%d%d", &N, &K);
  scanf("%d%d", &S, &T);
  for (__typeof(N) i = (0), __tmpvar__end252 = (N); i < __tmpvar__end252; i++) {
    scanf("%d%d", &cars[i].first, &cars[i].second);
  }
  vector<int> stops;
  for (__typeof(K) i = (0), __tmpvar__end254 = (K); i < __tmpvar__end254; i++) {
    int x;
    scanf("%d", &x);
    stops.push_back(x);
  }
  sort((stops).begin(), (stops).end());
  int cur = 0;
  for (auto &x : stops) {
    dists.push_back(x - cur);
    cur = x;
  }
  dists.push_back(S - stops.back());
  long long minv =
      binary_search_first_good((long long)1, (long long)2e9, isgood);
  1;
  if (minv == -1) {
    printf("-1");
    exit(0);
  };
  int ans = -1;
  for (__typeof(N) i = (0), __tmpvar__end271 = (N); i < __tmpvar__end271; i++) {
    if (cars[i].second >= minv) {
      if (ans == -1)
        ans = cars[i].first;
      else
        ans = min(ans, cars[i].first);
    }
  }
  PRN(ans);
  return 0;
}
