纪念品分组

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MaxN = 30010;
ll n,m,ans;
ll a[MaxN];
int main(){
	cin >> m >> n;
	for(ll i = 1;i <= n;i ++) cin >> a[i];
	sort(a + 1,a + n + 1);
	for(ll j = 1,i = n;i >= j;i --){
		if(a[i] + a[j] <= m) j ++;
		ans ++;
	}
	cout << ans << endl;
	return 0;
}