#include <bits/stdc++.h>
using namespace std;
int n, a[100001], i, j, d[100001], m, col;
int main() {
  cin >> n >> m;
  for (i = 1; i <= n; i++) cin >> d[i];
  for (j = 1; j <= m; j++) cin >> a[j];
  sort(a + 1, a + m + 1);
  for (i = 1; i <= n; i++)
    for (j = 1; j <= m; j++)
      if (a[j] >= d[i]) {
        a[j] = -1;
        col++;
        break;
      }
  cout << n - col;
  return 0;
}
