#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  while (cin >> n >> m) {
    int good[3005], all[3005];
    for (int i = 0; i < n; i++) cin >> good[i];
    for (int i = 0; i < m; i++) cin >> all[i];
    bool vis[3005];
    memset(vis, 0, sizeof(vis));
    int additionalProblems = 0;
    for (int i = n - 1; i >= 0; --i) {
      bool found = false;
      for (int j = m - 1; j >= 0; --j) {
        if (all[j] >= good[i] && !vis[j]) {
          found = true;
          vis[j] = 1;
          break;
        }
      }
      if (!found) additionalProblems++;
    }
    cout << additionalProblems << endl;
  }
  return 0;
}
