#include <bits/stdc++.h>
using namespace std;
int mod = 1e9 + 7;
long long powmod(long long a, long long b) {
  long long res = 1;
  if (a >= mod) a %= mod;
  for (; b; b >>= 1) {
    if (b & 1) res = res * a;
    if (res >= mod) res %= mod;
    a = a * a;
    if (a >= mod) a %= mod;
  }
  return res;
}
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
static struct IO {
  char tmp[1 << 10];
  char cur;
  inline char nextChar() { return cur = getc(stdin); }
  inline char peekChar() { return cur; }
  inline operator bool() { return peekChar(); }
  inline static bool isBlank(char c) { return (c < '-' && c); }
  inline bool skipBlanks() {
    while (isBlank(nextChar()))
      ;
    return peekChar() != 0;
  }
  inline IO& operator>>(char& c) {
    c = nextChar();
    return *this;
  }
  inline IO& operator>>(char* buf) {
    if (skipBlanks()) {
      if (peekChar()) {
        *(buf++) = peekChar();
        while (!isBlank(nextChar())) *(buf++) = peekChar();
      }
      *(buf++) = 0;
    }
    return *this;
  }
  inline IO& operator>>(string& s) {
    if (skipBlanks()) {
      s.clear();
      s += peekChar();
      while (!isBlank(nextChar())) s += peekChar();
    }
    return *this;
  }
  inline IO& operator>>(double& d) {
    if ((*this) >> tmp) sscanf(tmp, "%lf", &d);
    return *this;
  }
  inline IO& operator>>(int& n) {
    if (skipBlanks()) {
      int sign = +1;
      if (peekChar() == '-') {
        sign = -1;
        n = nextChar() - '0';
      } else
        n = peekChar() - '0';
      while (!isBlank(nextChar())) {
        n += n + (n << 3) + peekChar() - 48;
      }
      n *= sign;
    }
    return *this;
  }
  inline IO& operator>>(unsigned int& n) {
    if (skipBlanks()) {
      int sign = +1;
      if (peekChar() == '-') {
        sign = -1;
        n = nextChar() - '0';
      } else
        n = peekChar() - '0';
      while (!isBlank(nextChar())) {
        n += n + (n << 3) + peekChar() - 48;
      }
      n *= sign;
    }
    return *this;
  }
  inline IO& operator>>(long long& n) {
    if (skipBlanks()) {
      int sign = +1;
      if (peekChar() == '-') {
        sign = -1;
        n = nextChar() - '0';
      } else
        n = peekChar() - '0';
      while (!isBlank(nextChar())) {
        n += n + (n << 3) + peekChar() - 48;
      }
      n *= sign;
    }
    return *this;
  }
  inline void putChar(char c) { putc(c, stdout); }
  inline IO& operator<<(char c) {
    putChar(c);
    return *this;
  }
  inline IO& operator<<(const char* s) {
    while (*s) putChar(*s++);
    return *this;
  }
  inline IO& operator<<(const string& s) {
    for (int i = 0; i < (int)s.size(); ++i) putChar(s[i]);
    return *this;
  }
  char* toString(double d) {
    sprintf(tmp, "%lf%c", d, '\0');
    return tmp;
  }
  inline IO& operator<<(double d) { return (*this) << toString(d); }
  inline char* toString(int n) {
    char* p = (tmp + 30);
    if (n) {
      bool isNeg = 0;
      if (n < 0) isNeg = 1, n = -n;
      while (n) *--p = (n % 10) + '0', n /= 10;
      if (isNeg) *--p = '-';
    } else
      *--p = '0';
    return p;
  }
  inline IO& operator<<(int n) { return (*this) << toString(n); }
  inline char* toString(long long n) {
    char* p = (tmp + 30);
    if (n) {
      bool isNeg = 0;
      if (n < 0) isNeg = 1, n = -n;
      while (n) *--p = (n % 10) + '0', n /= 10;
      if (isNeg) *--p = '-';
    } else
      *--p = '0';
    return p;
  }
  inline IO& operator<<(long long n) { return (*this) << toString(n); }
} __io__;
const int N = 200000 + 5;
long long n, k, s, t, len[N], c[N], v[N], g[N], sum[N];
int ans = mod;
long long maxlen;
inline bool ok(long long cap) {
  long long tim = 0;
  int idx = upper_bound(len, len + k, cap / 2) - len;
  if (idx) tim += sum[idx - 1];
  if (idx != k) {
    tim -= cap * 1LL * (k - idx);
    tim += 3 * sum[k - 1];
    if (idx) tim -= 3 * sum[idx - 1];
  }
  return tim <= t;
}
int main() {
  int i, j;
  __io__ >> n >> k >> s >> t;
  for (i = 0; i < n; i++) {
    __io__ >> c[i] >> v[i];
  }
  for (i = 0; i < k; i++) {
    __io__ >> g[i];
  }
  sort(g, g + k);
  g[k] = s;
  int last = 0;
  for (i = 0; i <= k; i++) {
    len[i] = g[i] - last;
    last = g[i];
    maxlen = max(maxlen, len[i]);
  }
  k++;
  sort(len, len + k);
  sum[0] = len[0];
  for (i = 1; i < k; i++) sum[i] = len[i] + sum[i - 1];
  for (i = 0; i < n; i++) {
    if (v[i] >= maxlen && ans > c[i] && ok(v[i])) ans = c[i];
  }
  if (ans == mod) ans = -1;
  __io__ << ans << ('\n');
  return 0;
}
