#include <bits/stdc++.h>
using namespace std;
vector<int> arr1;
int a, b, x;
int main() {
  cin >> a >> b;
  arr1.resize(a);
  for (int i = 0; i < a; i++) cin >> arr1[i];
  sort(arr1.begin(), arr1.end());
  for (int i = 0; i < b; i++) {
    cin >> x;
    for (int k = 0; k < arr1.size(); k++)
      if (arr1[k] <= x) {
        arr1.erase(arr1.begin() + k);
        break;
      }
  }
  cout << arr1.size();
  return 0;
}
