#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M;
  int Y0, Y1;
  cin >> N >> M >> Y0 >> Y1;
  long long int a[N + 1];
  long long int b[M + 1];
  for (int i = 0; i < N; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < M; i++) {
    cin >> b[i];
  }
  long long int last_eaten = -1;
  int j = 0;
  int eaten = 0;
  for (int i = 0; i < N; i++) {
    while (j < M && abs(a[i] - b[j + 1]) < abs(a[i] - b[j])) {
      j++;
    }
    if (last_eaten < j || (i > 0 && abs(a[i - 1] - b[j]) == abs(a[i] - b[j]))) {
      eaten++;
      last_eaten = j;
    } else if (j < M && i < N && abs(a[i] - b[j]) == abs(a[i] - b[j + 1])) {
      eaten++;
      last_eaten = ++j;
    } else {
      last_eaten = j;
    }
  }
  cout << N - eaten;
  return 0;
}
