#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int n, m, ans;
vector <int> a(5e5, 0);
vector <int> b;
vector <int> dp(5e5, 1e9);
vector <int> f(5e5, 1e9);

int gr(int x) {
	return b.end() - lower_bound(b.begin(), b.end(), x);
}

int pos(int k) {
	return n + m - k - gr(a[k]);
}

void update(int k) {
	int x = pos(k);
	for (int i = x; i < f.size(); i = (i | (i + 1))) f[i] = min(f[i], dp[k]);
}

void query(int k) {
	int x = pos(k) + 1;
	for (int i = x; i >= 0; i = (i & (i + 1)) - 1) dp[k] = min(dp[k], f[i]);
	dp[k]--;
	if (gr(a[k]) >= n - k) ans = min(ans, dp[k]);
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cin >> n >> m;
	for (int i = 1; i <= n; i++) cin >> a[i];
	b.resize(m);
	for (int& i : b) cin >> i;
	sort(b.begin(), b.end());
	ans = m;
	dp[0] = n;
	for (int i = 1; i <= n; i++) {
		if (a[i - 1] < a[i]) dp[i] = dp[i - 1];
		query(i);
		update(i - 1);
	}
	cout << ans << "\n";
	/*for (int i = 0; i <= n; i++) cout << pos(i) << " ";
	cout << "\n";
	for (int i = 0; i <= n; i++) cout << dp[i] << " ";*/
}