#include<bits/stdc++.h>
using namespace std;
const int M = 100000;
int w;
int n;
int a[M];
int main(){
	freopen("group.in","r",stdin);
	freopen("group.out","w",stdout);
 	cin>>w>>n;
 	for(int i = 1; i<=n; i++){
  		cin>>a[i];
 	}
 	sort(a+1, a+n+1);
 	int ans = 0;
 	int l = 1, r = n;
 	while(l<=r){
	  	if(a[l]+a[r] <= w && l!=r){
	   		ans++;
	   		r--;
	   		l++;
	  	}
	  	else{
	   		ans++;
	   		r--;
	  	}
 	}
 	cout<<ans;
 	return 0;
}