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 double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;
const int maxn = 200005;
int i, j, m, n, s;
long long t;
struct car {
  int cost, v;
} c[maxn];
int kk[maxn];
bool check(long long x) {
  long long tot = 0;
  for (int i = 1; i <= m; i++) {
    long long t1 = kk[i] - kk[i - 1];
    if (2 * t1 <= x) {
      tot += t1;
      continue;
    }
    if (t1 > x) return false;
    tot += (x - t1) + 2 * (2 * t1 - x);
  }
  return tot <= t;
}
int find() {
  long long l = 1, r = 1e9;
  while (r - l > 1) {
    int mid = (l + r) >> 1;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  if (!check(l)) l++;
  return l;
}
int main() {
  scanf("%d%d%d%lld", &n, &m, &s, &t);
  for (i = 1; i <= n; i++) scanf("%d%d", &c[i].cost, &c[i].v);
  for (i = 1; i <= m; i++) scanf("%d", &kk[i]);
  sort(kk + 1, kk + m + 1);
  kk[0] = 0;
  kk[++m] = s;
  int d = find();
  int ans = 1e9 + 7;
  for (i = 1; i <= n; i++)
    if (c[i].v >= d) ans = min(ans, c[i].cost);
  if (ans < 1e9 + 7)
    printf("%d", ans);
  else
    printf("-1");
  return 0;
}
