#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<int> contest;
  vector<int> question;
  for (int i = 0; i < n; i++) {
    int t;
    cin >> t;
    contest.push_back(t);
  }
  for (int i = 0; i < m; i++) {
    int t;
    cin >> t;
    question.push_back(t);
  }
  sort(contest.begin(), contest.end());
  sort(question.begin(), question.end());
  int pointer1 = n - 1;
  int pointer2 = m - 1;
  int count = 0;
  while (pointer1 >= 0 && pointer2 >= 0) {
    if (question[pointer2] >= contest[pointer1]) {
      pointer2--;
      pointer1--;
    } else {
      count++;
      pointer1--;
    }
  }
  if (pointer1 > 0) {
    count += pointer1 + 1;
  }
  if (count + m < n) {
    count += n - (count + m);
  }
  cout << count << endl;
}
