#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[1000050] = {0};
  int b[1000050] = {0};
  int n, m, t, k = 0;
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> t;
    a[t]++;
  }
  for (int i = 0; i < m; i++) {
    cin >> t;
    b[t]++;
  }
  for (int i = 0; i < 1000050; i++) {
    k = k + a[i];
    k = max(0, k - b[i]);
  }
  cout << k;
  return 0;
}
