#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int i, j, k;
  long long int n, m, count;
  cin >> n >> m;
  long long int a[n], b[m];
  for (i = 0; i < n; i++) cin >> a[i];
  for (i = 0; i < m; i++) cin >> b[i];
  for (i = 0; i < n; i++) {
    for (j = 0; j < m; j++) {
      if (a[i] == b[j]) {
        a[i] = -1, b[j] = -1;
        break;
      }
    }
  }
  for (i = 0; i < n; i++) {
    if (a[i] != -1) {
      for (j = 0; j < m; j++) {
        if (b[j] != -1 && b[j] > a[i]) {
          a[i] = -1;
          b[j] = -1;
          break;
        }
      }
    }
  }
  count = 0;
  for (i = 0; i < n; i++) {
    if (a[i] != -1) count++;
  }
  cout << count << endl;
  return 0;
}
