#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  int *a, *b;
  a = new int[n];
  b = new int[m];
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < m; i++) cin >> b[i];
  sort(a, a + n);
  sort(b, b + m);
  int j = 0, k = 0;
  int count;
  for (int i = 0; i < m; i++) {
    if (j >= n) break;
    if (a[j] <= b[k])
      j++, k++;
    else
      k++;
  }
  cout << n - j << "\n";
  return 0;
}
