#include<bits/stdc++.h>
using namespace std;
const int M = 100000;
int w=0;
int n=0;
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;
}