#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<int> a;
  vector<int> b;
  int n, m;
  cin >> n;
  cin >> m;
  a.resize(n);
  b.resize(m);
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    a[i] = x;
  }
  for (int i = 0; i < m; i++) {
    int x;
    cin >> x;
    b[i] = x;
  }
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  int ans = 0;
  int j = 0, i;
  for (i = 0; j < m;) {
    if (a[i] < b[j]) {
      i++;
      j++;
    } else if (a[i] == b[j]) {
      j++;
      i++;
    } else
      j++;
  }
  ans = n - i;
  if (ans < 0) ans = 0;
  cout << ans;
}
