#include <bits/stdc++.h>
using namespace std;
const int sz = 1e3;
int adjm[sz + 1][sz + 1];
vector<int> adjl[(int)(1e6 + 1)];
vector<bool> vis((int)1e6 + 1, 0);
void init_adjm(int n) {
  for (int i = 0; i <= n; i++) {
    for (int j = 0; j <= n; j++) adjm[i][j] = 0;
  }
}
void bfs(int s, int n, int m) {
  queue<int> q;
  q.push(s);
  q.push(-1);
  vis[s] = 1;
  while (!q.empty()) {
    int p = q.front();
    q.pop();
    if (p == -1) {
      if (!q.empty()) {
        q.push(-1);
      }
    } else {
      for (int i = 0; i < adjl[p].size(); i++) {
        int curr{adjl[p][i]};
        if (!vis[curr]) {
          q.push(curr);
          vis[curr] = 1;
        }
      }
    }
  }
}
void dfs(int s) {
  vis[s] = 1;
  for (int i{0}; i < adjl[s].size(); i++) {
    if (!vis[adjl[s][i]]) {
      dfs(adjl[s][i]);
    }
  }
}
vector<bool> is_prime(1e6 + 1, true);
long long gcd(long long x, long long y) {
  if (x == 0) return y;
  return gcd(y % x, x);
}
void sievePrime(long long n) {
  for (long long p{2}; p * p <= n; p++) {
    if (is_prime[p]) {
      for (long long i{p * p}; i <= n; i += p) {
        is_prime[i] = false;
      }
    }
  }
}
vector<int> SPF((int)1e6 + 1);
vector<long long> prime;
void manipulated_seive(int N) {
  is_prime[0] = is_prime[1] = false;
  for (int i = 2; i < N; i++) {
    if (is_prime[i]) {
      prime.push_back(i);
      SPF[i] = i;
    }
    for (int j{0};
         j < (int)prime.size() && i * prime[j] < N && prime[j] <= SPF[i]; j++) {
      is_prime[i * prime[j]] = false;
      SPF[i * prime[j]] = prime[j];
    }
  }
}
class my_compare {
 public:
  bool operator()(pair<int, int> &p1, pair<int, int> &p2) {
    return p1.second < p2.second;
  }
};
long long fact(int n) {
  long long res{1};
  for (int i = 2; i <= n; i++) res *= i;
  return res;
}
long long nPr(int n, int r) {
  long long num{1}, denom{1};
  for (int i = 0; i < r; i++) {
    denom *= (i + 1);
    num *= (n - i);
  }
  return num / denom;
}
long long nCr(int n, int r) {
  long long num{1}, denom{1};
  for (int i = 0; i < r; i++) {
    denom = (denom * (i + 1));
    num = (num * (n - i));
  }
  return num / denom;
}
unsigned long long power(unsigned long long x, int y, int p) {
  unsigned long long res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
unsigned long long modInverse(unsigned long long n, int p) {
  return power(n, p - 2, p);
}
unsigned long long nCrModPFermat(unsigned long long n, int r, int p) {
  if (n < r) return 0;
  if (r == 0) return 1;
  unsigned long long fac[n + 1];
  fac[0] = 1;
  for (int i = 1; i <= n; i++) fac[i] = (fac[i - 1] * i) % p;
  return (fac[n] * (modInverse(fac[r], p) % p) *
          (modInverse(fac[n - r], p) % p)) %
         p;
}
void solve() {
  int n, m, x;
  cin >> n >> m;
  multiset<int, greater<int>> reqd;
  for (int i = 0; i < n; i++) {
    cin >> x;
    reqd.insert(x);
  }
  for (int i = 0; i < m; i++) {
    cin >> x;
    auto it = reqd.lower_bound(x);
    if (it != reqd.end()) {
      reqd.erase(it);
    }
  }
  cout << reqd.size() << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  bool test_case{0}, fileop{0};
  if (fileop) {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  }
  int t;
  if (test_case) {
    cin >> t;
    while (t--) {
      solve();
    }
  } else
    solve();
}
