#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
const int INF = 1e9;
const int MOD = 1e9 + 7;
const int M = INF;
const double RRR = 180.0 / PI;
int main() {
  double TIME_START = clock();
  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<int> b(m);
  for (int i = 0; i < m; i++) {
    cin >> b[i];
  }
  vector<int> used(m, 0);
  vector<int> aus(n, 0);
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  reverse(a.begin(), a.end());
  reverse(b.begin(), b.end());
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (a[i] == b[j] && used[j] == 0) {
        used[j] = 1;
        aus[i] = 1;
        break;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    if (aus[i] == 0) {
      for (int j = 0; j < m; j++) {
        if (used[j] == 0 && b[j] >= a[i]) {
          aus[i] = 1;
          used[j] = 1;
          break;
        }
      }
    }
  }
  int ans = 0;
  for (int i = 0; i < n; i++) {
    if (aus[i] == 0) {
      ans++;
    }
  }
  cout << ans;
  return 0;
}
