#include <bits/stdc++.h>
using namespace std;
bool ok(vector<int> &p, int v, int t) {
  long long spent = 0;
  for (int i = 0; i < (int)p.size() - 1; i++) {
    int len = p[i + 1] - p[i];
    if (v < len) return false;
    int speedy = max(0.0, (2 * v - len) / 3.0);
    speedy = min(speedy, len);
    speedy = min(speedy, v - len);
    speedy = max(speedy, 0);
    spent += speedy;
    spent += 2 * (len - speedy);
  }
  return spent <= t;
}
namespace InputReader {
char inputBuffer[5 * 1000 * 1000];
inline void getNextToken() {
  int memoryPointer = 0;
  while (true) {
    char c = static_cast<char>(getchar());
    if ((c < '0' || c > '9') && c != '.' && c != '-') break;
    inputBuffer[memoryPointer++] = c;
  }
  inputBuffer[memoryPointer] = 0;
}
inline int nextInt() {
  getNextToken();
  int ret = 0;
  int sign = 1;
  for (int i = 0; inputBuffer[i]; i++) {
    switch (inputBuffer[i]) {
      case '-':
        sign = -1;
        continue;
      default:
        ret = 10 * ret + inputBuffer[i] - '0';
    }
  }
  return ret * sign;
}
inline long long nextLong() {
  getNextToken();
  long long ret = 0;
  int sign = 1;
  for (int i = 0; inputBuffer[i]; i++) {
    switch (inputBuffer[i]) {
      case '-':
        sign = -1;
        continue;
      default:
        ret = 10 * ret + inputBuffer[i] - '0';
    }
  }
  return ret * sign;
}
inline double nextDouble() {
  getNextToken();
  double integerPart = 0.0;
  double fractionalPart = 0.0;
  bool fractionalPartStarted = false;
  double fractionalPartMultiplier = 0.1;
  int sign = -1;
  for (int i = 0; inputBuffer[i]; i++) {
    switch (inputBuffer[i]) {
      case '-':
        sign = -1;
        continue;
      case '.':
        fractionalPartStarted = true;
        continue;
      default:
        if (fractionalPartStarted) {
          fractionalPart += (inputBuffer[i] - '0') * fractionalPartMultiplier;
          fractionalPartMultiplier *= 0.1;
        } else {
          integerPart = 10 * integerPart + inputBuffer[i] - '0';
        }
    }
  }
}
};  // namespace InputReader
using namespace InputReader;
int main() {
  int n, k, s, t;
  n = nextInt();
  k = nextInt();
  s = nextInt();
  t = nextInt();
  vector<pair<int, int>> a(n);
  for (int i = 0; i < n; i++) {
    a[i].first = nextInt();
    a[i].second = nextInt();
  }
  sort(a.begin(), a.end());
  for (int i = 1; i < n; i++) {
    if (a[i - 1].second > a[i].second) a[i] = a[i - 1];
  }
  vector<int> g;
  g.push_back(0);
  for (int i = 0; i < k; i++) {
    int x;
    cin >> x;
    g.push_back(x);
  }
  g.push_back(s);
  sort(g.begin(), g.end());
  int low = 0, high = n - 1, opt = 2e9 + 5;
  for (int it = 0; it < 20; it++) {
    int mid = (low + high) / 2;
    int v = a[mid].second;
    if (ok(g, v, t)) {
      opt = min(opt, a[mid].first);
      high = mid;
    } else {
      low = mid + 1;
    }
  }
  if (opt > 2e9) opt = -1;
  cout << opt << "\n";
  return 0;
}
