#include <bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
const int maxn = 100010;
int x0[maxn], x1[maxn], d[maxn], c[maxn];
int main() {
  int n, m, y0, y1;
  scanf("%d %d %d %d", &n, &m, &y0, &y1);
  for (int i = 0; i < n; ++i) {
    scanf("%d", &x0[i]);
  }
  memset(d, -1, sizeof(d));
  for (int i = 0; i < m; ++i) {
    scanf("%d", &x1[i]);
  }
  int p = 0, k = 0, last = -1;
  for (int i = 0; i < n; ++i) {
    while (p < m && abs(x0[i] - x1[p]) > abs(x0[i] - x1[p + 1])) ++p;
    if (last < p || abs(x0[i - 1] - x1[p]) == abs(x0[i] - x1[p]))
      ++k, last = p;
    else if (p < m && abs(x0[i] - x1[p]) == abs(x0[i] - x1[p + 1]))
      ++k, last = ++p;
    else
      last = p;
  }
  printf("%d\n", n - k);
  return 0;
}
