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