#include <bits/stdc++.h>
using namespace std;
int ches[100010];
int mice[100010];
int n, m;
int main() {
  int i, x, y, j;
  scanf("%d %d %d %d", &n, &m, &x, &y);
  for (i = 0; i < n; i++) {
    scanf("%d", &mice[i]);
  }
  for (j = 0; j < m; j++) {
    scanf("%d", &ches[j]);
  }
  int last = -1, res = 0;
  j = 0;
  for (i = 0; i < n; i++) {
    while (j < m && abs(mice[i] - ches[j]) > abs(mice[i] - ches[j + 1])) {
      j++;
    }
    if (j != last || abs(mice[i] - ches[j]) == abs(mice[i - 1] - ches[j])) {
      last = j;
      res++;
    } else if (j + 1 < m &&
               abs(mice[i] - ches[j]) == abs(mice[i] - ches[j + 1])) {
      res++;
      last = ++j;
    } else {
      last = j;
    }
  }
  printf("%d", n - res);
}
