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 = 2 * 1e5 + 500;
const int m = 1 * 1e2 + 50;
int N;
int K;
int S;
int T;
int optimal_cap, best = -1;
int cost[n], cap[n], gas[n];
bool ok(int op) {
  int ind = 1, mn_T = 0, last = 0;
  while (ind <= K + 1) {
    int d = gas[ind] - last;
    if (d > op) return 0;
    int inc = 2 * d;
    int rem = op - d;
    inc -= min(d, rem);
    mn_T += inc;
    last = gas[ind];
    ind++;
  }
  return (mn_T <= T);
}
int main() {
  scanf("%d%d%d%d", &N, &K, &S, &T);
  for (int i = 1; i <= N; i++) {
    scanf("%d%d", cost + i, cap + i);
  }
  for (int i = 1; i <= K; i++) {
    scanf("%d", gas + i);
  }
  sort(gas, gas + K + 1);
  gas[K + 1] = S;
  int l = 1, r = 2e9;
  while (l < r) {
    int m = l + (r - l) / 2;
    if (ok(m)) {
      r = m;
    } else {
      l = m + 1;
    }
  }
  optimal_cap = r;
  for (int i = 1; i <= N; i++) {
    if (cap[i] >= optimal_cap) {
      if (best == -1)
        best = cost[i];
      else
        best = min(best, cost[i]);
    }
  }
  printf("%d", best);
  return 0;
}
