#include<iostream>
#include<vector>
#include<map>
#include<set>
#include<cassert>
#include<cassert>
#include<unordered_map>
#include<unordered_set>
#include<functional>
#include<queue>
#include<stack>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<sstream>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
#include<numeric>
#include<random>
#include<chrono>
#include<bitset>
using namespace std;

#define all(x) (x).begin(), (x).end()
#define pb push_back
#define xx first
#define yy second
#define sz(x) (int)(x).size()
#define gc getchar
#define IO ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define mp make_pair

#ifndef ONLINE_JUDGE
#  define LOG(x) (cerr << #x << " = " << (x) << endl)
#else
#  define LOG(x) ((void)0)
#endif

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

const double PI=acos(-1);
const ll INF = 1LL<<62;
const ll MINF = -(1LL<<62);

template<typename T> T getint() {
	T val=0;
	char c;
	
	bool neg=false;
	while((c=gc()) && !(c>='0' && c<='9')) {
		neg|=c=='-';
	}

	do {
		val=(val*10)+c-'0';
	} while((c=gc()) && (c>='0' && c<='9'));

	return val*(neg?-1:1);
}

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); uniform_int_distribution<int>(0, n-1)(rng)
vector<int> a,b,pos;
vector<int> dp;

vector<int> solve(int l, int r) {
	if(l==r) {
		if(pos[l]>=l) dp[l]=max(dp[l], 1);
		return {l};
	}
	
	int mid=(l+r)/2;
	vector<int> lst=solve(l, mid);
	lst.reserve(r-l+1);
	
	if(mid+1<=r) {
		for(int i=mid+1;i<=r;++i) lst.pb(i);
		
		sort(lst.begin()+mid+1-l, lst.end(), [&](int x, int y) -> bool {
			return a[x]<a[y];
		});
		
		
	}

	inplace_merge(lst.begin(),lst.begin()+mid+1-l,lst.end(), [&](int x, int y) -> bool {
		return a[x]<a[y];
	});
	
	set<pair<int,int>> st; //{i-pos[i], dp[i]}
	for(auto i:lst) {
		if(i<=mid) {
			st.insert(mp(i-pos[i], dp[i]));
			auto it=st.lower_bound(mp(i-pos[i], dp[i]));
			while(it!=st.begin() && prev(it)->yy<=it->yy) st.erase(prev(it));
			if(next(it)!=st.end() && next(it)->yy>=it->yy) st.erase(it);
		}else {
			auto it=st.lower_bound(mp(i-pos[i]-1, 0));
			if(it!=st.end()) {
				dp[i]=max(dp[i], it->yy+1);
			}
		}
	}
	
	solve(mid+1, r);
	return lst;
}

int main() {
	IO;
	int n,m;
	cin>>n>>m;
	a=vector<int>(n);
	b=vector<int>(m);
	for(int i=0;i<n;++i) {
		cin>>a[i];
	}
	
	for(int i=0;i<m;++i) {
		cin>>b[i];
	}
	
	n++;
	a.pb(1e9+1);
	
	sort(all(b));
	
	pos=vector<int>(n);
	for(int i=0;i<n;++i) {
		pos[i]=lower_bound(all(b),a[i])-b.begin();
	}
	
	dp=vector<int>(n,-1e9);

	solve(0,n-1);
	cout<<n-dp[n-1]<<"\n";
		
	return 0;
}