1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

#include <bits/stdc++.h>
using namespace std;
const int iinf = 1e9 + 7;
const long long linf = 1ll << 60;
const double dinf = 1e10;
template <typename T>
inline void scf(T &x) {
  bool f = 0;
  x = 0;
  char c = getchar();
  while ((c < '0' || c > '9') && c != '-') c = getchar();
  if (c == '-') {
    f = 1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  if (f) x = -x;
  return;
}
template <typename T1, typename T2>
void scf(T1 &x, T2 &y) {
  scf(x);
  return scf(y);
}
template <typename T1, typename T2, typename T3>
void scf(T1 &x, T2 &y, T3 &z) {
  scf(x);
  scf(y);
  return scf(z);
}
const int N = 2e5 + 100;
int n, k, s, t;
pair<int, int> car[N];
int pos[N];
vector<pair<int, int> > tmp;
inline bool cmp(pair<int, int> x, pair<int, int> y) {
  return x.first == y.first ? x.second > y.second : x.first < y.first;
}
inline bool check(int V) {
  int ret = 0;
  for (int i = (1); i <= (k - 1); i++) {
    int d = pos[i] - pos[i - 1];
    if (d > V) return 0;
    int calc = V - d;
    if (calc > d) calc = d;
    ret += calc + (d - calc) * 2;
  }
  return ret <= t;
}
int main() {
  scf(n, k);
  scf(s, t);
  for (int i = 0; i < (n); i++) {
    int x, y;
    scf(x, y);
    car[i] = make_pair(x, y);
  }
  sort(car, car + n, cmp);
  for (int i = 0; i < (n); i++)
    if (!i || car[i].first != car[i - 1].first) tmp.push_back(car[i]);
  for (int i = 0; i < (k); i++) scf(pos[i]);
  pos[k++] = 0;
  pos[k++] = s;
  sort(pos, pos + k);
  n = (int)tmp.size();
  int lb = 0, rb = n - 1;
  while (lb <= rb) {
    int mid = lb + rb >> 1;
    if (check(tmp[mid].second))
      rb = mid - 1;
    else
      lb = mid + 1;
  }
  printf("%d\n", (lb == n) ? -1 : tmp[lb].first);
  return 0;
}
