#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int a[N], b[N], d[N], used[N], dis[N], ANS[N], dlt[N];
int n, m, Y0, Y1, lft, ans;
vector<int> ch[N], fa[N];
priority_queue<pair<int, int>, vector<pair<int, int> >,
               greater<pair<int, int> > >
    pq;
int ABS(int x) {
  if (x >= 0)
    return x;
  else
    return -x;
}
int lnk(int x, int y) {
  ch[x].push_back(y);
  fa[y].push_back(x);
  return ABS(b[x] - a[y]);
}
int avi(int x) {
  int ret = 0;
  for (int i = 0; i < int(fa[x].size()); i++) {
    int to = fa[x][i];
    if (used[to] == -1 || used[to] == dis[x]) ret++;
  }
  return ret;
}
int main() {
  scanf("%d%d%d%d", &n, &m, &Y0, &Y1);
  for (int i = 1; i <= n; i++) scanf("%d", a + i);
  for (int i = 1; i <= m; i++) scanf("%d", b + i);
  for (int i = 1; i <= m; i++) used[i] = -1;
  for (int i = 1; i <= n; i++) {
    int x = lower_bound(b + 1, b + 1 + m, a[i]) - b - 1;
    int y = x + 1;
    if (x == 0)
      dis[i] = lnk(y, i);
    else if (y == m + 1)
      dis[i] = lnk(x, i);
    else if (a[i] - b[x] < b[y] - a[i])
      dis[i] = lnk(x, i);
    else if (a[i] - b[x] > b[y] - a[i])
      dis[i] = lnk(y, i);
    else {
      dis[i] = lnk(x, i);
      lnk(y, i);
    }
    if (avi(i) == 1) {
      dlt[i] = 1;
      pq.push(make_pair(dis[i], i));
    }
  }
  lft = n;
  while (!pq.empty()) {
    int D = pq.top().first, x = pq.top().second, y;
    pq.pop();
    lft--;
    if (avi(x) == 0) continue;
    for (int i = 0; i < int(fa[x].size()); i++) {
      y = fa[x][i];
      if (used[y] == -1 || used[y] == D) break;
    }
    used[y] = D;
    ANS[y]++;
    for (int i = 0; i < int(ch[y].size()); i++) {
      int to = ch[y][i];
      if (dis[to] != D && !dlt[to] && avi(to) == 1) {
        dlt[to] = 1;
        pq.push(make_pair(dis[to], to));
      }
    }
  }
  for (int i = 1; i <= m; i++) ans += ANS[i];
  ans += lft;
  printf("%d\n", n - ans);
  return 0;
}
