自己看

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll w,ans=0;
ll n,a[30010];
int main(){
    //freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::cout.tie(nullptr);
    cin>>w>>n;
    for(ll i=1;i<=n;i++) cin>>a[i];
    sort(a+1,a+n+1);
    ll l=1,r=n;
    while(l<=r){
        if(a[l]+a[r]<=w){
            l++;
            r--;
            ans++;
        }else{
            r--;
            ans++;
        }
    }
    cout<<ans<<endl;
    //fclose(stdin);
	//fclose(stdout);
	return 0;
}
//coder::by::M91