//
//  main.cpp
//  寒假作业
//
//  Created by 宋玉良 on 2020/2/2.
//  Copyright © 2020 宋玉良. All rights reserved.
//

#include<iostream>
#include<algorithm>
#include<stdio.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--;
      }
     }
    printf("%d\n",ans);
    return 0;
}