/*P1094*/
/*
输入完之后
Process exited after 5.225 seconds with return value 3221225477
*/
#include<bits/stdc++.h>
#error Process exited after 5.225 seconds with return value 3221225477
#error 你们不知道我是故意的
using namespace std;
#define int long long
int n,m;
int cnt;
multiset<int>st;
signed main(){
    cin>>m>>n;
    m=-m;
    for(int i=1;i<=n;i++){
        int tmp;
        cin>>tmp;
        st.insert(-tmp);
    }
    for(multiset<int>::iterator i=st.begin();i!=st.end();i++){
        multiset<int>::iterator k=st.lower_bound(m-*i);
        if(k!=st.end()&&k!=i){
            st.erase(k);
        }
        st.erase(i);
        cnt++;
        if(i==st.end())break;
    }
    cout<<cnt;
	return 0;
}
#error 求调QAQ