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 INF = 0x3f3f3f3f;
const int msz = 10000;
const int mod = 1e9 + 7;
const double eps = 1e-8;
const int maxn = 212345;
struct Car {
  int c, v;
  bool operator<(const struct Car a) const {
    return c == a.c ? v > a.v : c < a.c;
  }
} cr[maxn], us[maxn];
int tp;
int k, s, t;
int g[maxn];
long long got(int dis, int v) {
  int l = 0, r = dis;
  long long ans = -1;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (2 * mid + (dis - mid) <= v) {
      ans = mid + 2 * (dis - mid);
      l = mid + 1;
    } else
      r = mid - 1;
  }
  return ans;
}
bool cal(int v) {
  long long ned = 0;
  for (int i = 1; i <= k; ++i) {
    int dis = g[i] - g[i - 1];
    if (dis > v) return false;
    long long now = got(dis, v);
    if (now == -1) return false;
    ned += now;
  }
  return ned <= t;
}
int main() {
  int n;
  tp = 0;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; ++i) scanf("%d%d", &cr[i].c, &cr[i].v);
  g[0] = 0;
  for (int i = 1; i <= k; ++i) scanf("%d", &g[i]);
  g[++k] = s;
  sort(g, g + k + 1);
  sort(cr, cr + n);
  int mx = cr[0].v;
  for (int i = 0; i < n; ++i) {
    if (i == 0 || cr[i].v > mx) {
      us[tp++] = cr[i];
      mx = cr[i].v;
    }
  }
  int ans = -1;
  int l, r;
  l = 0, r = tp - 1;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (cal(us[mid].v)) {
      ans = us[mid].c;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  printf("%d\n", ans);
  return 0;
}
