#include <bits/stdc++.h>
using namespace std;
int n, m, X, Y;
int pm[(1 << 17)], pc[(1 << 17)];
int mmd[(1 << 17)], ddt[(1 << 17)];
int mrk[(1 << 17)];
int Ans;
int main() {
  scanf("%d%d%d%d", &n, &m, &X, &Y);
  for (int i = 0; i < n; i++) {
    scanf("%d", &pm[i]);
  }
  for (int i = 0; i < m; i++) {
    scanf("%d", &pc[i]);
    mmd[i] = (2147483647);
  }
  int curx = 0, cury = 0;
  while (curx < n && cury < m) {
    int dist = abs(pm[curx] - pc[cury]);
    while (cury < m - 1 && dist > abs(pm[curx] - pc[cury + 1])) {
      cury++;
      dist = abs(pm[curx] - pc[cury]);
    }
    if (cury < m - 1 && dist == abs(pm[curx] - pc[cury + 1])) {
      if (dist == mmd[cury] || mmd[cury] == (2147483647)) {
        mrk[curx] = cury;
        mmd[cury] = min(mmd[cury], dist);
      } else {
        mrk[curx] = cury + 1;
        mmd[cury + 1] = min(mmd[cury + 1], dist);
      }
    } else {
      mrk[curx] = cury;
      mmd[cury] = min(mmd[cury], dist);
    }
    ddt[curx++] = dist;
  }
  for (int i = 0; i < n; i++) {
    if (ddt[i] == mmd[mrk[i]]) {
      Ans++;
    }
  }
  printf("%d\n", n - Ans);
  return 0;
}
