#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, i, flag, ans, index, j;
  int a[4000], b[4000];
  cin >> n >> m;
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < m; i++) cin >> b[i];
  ans = 0;
  for (i = n; i >= 0; i--) {
    flag = 0;
    for (j = m; j >= 0; j--) {
      if (a[i] <= b[j]) {
        flag = 1;
        b[j] = 0;
        break;
      }
    }
    if (flag == 0) ans = ans + 1;
  }
  cout << ans;
  return 0;
}
