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 N = 2e5 + 5;
const int INF = 2e9;
int n, k, s, t;
struct car {
  int c;
  int v;
} a[N];
int g[N];
int min_reservoir = INF;
bool check(int fuel) {
  int i;
  long long time = 0;
  long long x;
  for (i = 1; i <= k + 1; i++) {
    if (fuel <= g[i] - g[i - 1]) return false;
    x = (g[i] - g[i - 1]) * 2;
    x -= min(g[i] - g[i - 1], fuel - (g[i] - g[i - 1]));
    time += x;
  }
  return time <= t;
}
int ans = INF;
int main() {
  int i;
  int low, high, mid;
  cin >> n >> k >> s >> t;
  for (i = 1; i <= n; i++) {
    scanf("%d%d", &a[i].c, &a[i].v);
  }
  for (i = 1; i <= k; i++) {
    scanf("%d", &g[i]);
  }
  sort(g + 1, g + k + 1);
  g[k + 1] = s;
  low = 1;
  high = 1e9;
  while (low <= high) {
    mid = (low + high) / 2;
    if (check(mid)) {
      min_reservoir = mid;
      high = mid - 1;
    } else {
      low = mid + 1;
    }
  }
  for (i = 1; i <= n; i++) {
    if (a[i].v >= min_reservoir) {
      ans = min(ans, a[i].c);
    }
  }
  if (ans != INF)
    printf("%d\n", ans);
  else
    printf("-1\n");
  return 0;
}
