#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, i, j, ans = 0;
  int a[3002], b[3002];
  bool vis[3002];
  cin >> n >> m;
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < m; i++) cin >> b[i];
  memset(vis, 0, sizeof(vis));
  for (i = 0; i < n; i++) {
    for (j = 0; j < m; j++) {
      if (a[i] <= b[j] && vis[j] == 0) {
        ans++;
        vis[j] = 1;
        break;
      }
    }
  }
  cout << (n - ans) << "\n";
  return 0;
}
